Demographic Transition Theory

Family planning mainly affects the timing and number of births. When its use increases, couples may postpone births, leave a longer interval between children, or decide to have fewer children. These changes first influence the birth rate, also called the crude birth rate when measured per thousand people. They do not directly reduce deaths among people who are already alive. Population density and land area are also not rates that would respond immediately to wider contraceptive use.

Option A is therefore correct. Mortality is already low in the situation described, so a sudden expansion of family planning would not normally produce the clearest first change in mortality. The effect on births may appear relatively quickly in annual vital statistics, although the total population may continue to grow for some time because of population momentum. Thus the most direct early indicator is a fall in the birth rate.

Life expectancy rises when people survive longer, usually because mortality has fallen through better health care, nutrition, sanitation, or disease control. If the birth rate remains high, births continue to exceed deaths by a wide margin. The resulting natural increase becomes rapid, even though the country has begun to improve its health conditions.

This is the characteristic pattern of the second stage of demographic transition, so option A is correct. The third stage involves falling fertility and a slowing growth rate, while the first stage is associated with high mortality. Natural decline occurs only when deaths exceed births. Since the question states that fertility is unchanged and does not say it is low, the rapid-growth interpretation follows.

In rural economies, children may contribute to farm work or help support the household, so larger families can sometimes appear economically useful. Urban life changes this calculation. Children usually contribute less direct labour, while parents face higher costs for housing, education, transport, health care, and supervision. Women’s education and employment can also increase the opportunity cost of having many children.

As the perceived economic benefit of a large family falls, couples may choose fewer children and invest more in each child. A lower birth rate helps a society move from the high-fertility pattern of the second stage toward the third stage, where fertility declines while mortality is already low. Urbanization does not necessarily raise mortality or end migration, so option A is correct.

The second stage of demographic transition usually has a falling death rate, rising life expectancy, and a birth rate that remains high for some time. Because deaths decline before births decline substantially, the difference between births and deaths becomes large, producing rapid population growth. Better health care, sanitation, nutrition, and disease control explain the rise in life expectancy during this stage.

Option A is therefore the best answer. The first stage normally has both high birth and high death rates, so rapid growth is not its defining feature. In the third stage, fertility generally falls and population growth slows. A natural-decline stage has deaths exceeding births, which would produce decline rather than rapid growth. The question describes the characteristic combination of the second stage, although actual countries may pass through stages at different speeds.

A fall in fertility first reduces the number of babies being born; it does not remove the large groups of children who were born during earlier years of high fertility. As these existing young cohorts grow older, many of them enter working age at roughly the same time. Consequently, the working-age share can continue to rise for several years after fertility has begun to decline.

Option A is correct. This is a cohort effect and may create a demographic dividend if education, health, and employment opportunities are adequate. Lower fertility does not immediately shrink the labour force, because earlier births have already created people who are now approaching adulthood. The other options are not necessary consequences: mortality need not always rise, and the question gives no basis for assuming migration is zero.

Total population changes through both natural increase and net migration. Natural increase is calculated from births minus deaths. When birth and death rates are both low, this natural increase may be small, but it need not be zero. Strongly positive net migration means that considerably more people enter the country than leave it. Therefore, migration can add many people even when the resident population has relatively few births.

The relevant idea is that total population change equals natural increase plus net migration. If the natural increase is slightly positive, zero, or even somewhat negative, a strongly positive migration balance can still produce rapid overall growth. Thus option A is correct. Option B is too certain because migration can change the total, while option C confuses natural increase with migration; migration affects total growth, not the birth-minus-death rate itself. Fertility need not rise, so D is also unsupported.

Natural increase is calculated by subtracting the death rate from the birth rate. Here, the birth rate is 22 per thousand and the death rate is 6 per thousand. Therefore, the calculation is \(22-6=16\) per thousand. This means that, before considering migration, the population gains 16 persons per thousand people in the given period.

Option A is correct because the result is positive: births are more numerous than deaths. Adding the two rates would give 28, but that does not measure natural increase. Using only the death rate or only the birth rate also ignores the required difference. The exact demographic-transition stage cannot be fixed from these two rates alone, because the direction and level of fertility change are not given; however, the numerical natural-increase rate is unambiguously 16 per thousand.

Child dependency refers to the support needed by children from working-age adults. When fertility falls, there are fewer children in each household and the number of children needing schools, nutrition, health care, and daily support grows more slowly. Families may then have more money, time, and attention available for each child. Governments may also face less immediate pressure to expand child-related services simply because of rapid growth in the child population.

As a result, a larger share of available resources can potentially be spent on each child’s education, health, and nutrition. This is a possibility, not an automatic guarantee, because income distribution and public policy also matter. Option A is therefore correct. Lower fertility does not make schools unnecessary, does not raise mortality, and does not require investment per child to fall; those statements are unsupported.

Female employment can be associated with smaller families when fertility is also declining. Employment may delay marriage or childbearing, increase women’s time and income opportunities, and raise the opportunity cost of leaving work to care for many children. Families may also invest more resources in each child, making a smaller number of children preferable. These effects are possible tendencies, not guarantees for every household or country.

Option A is correct because a falling birth rate generally reduces the average number of children in a family. The other choices are not supported: family size does not have to increase, rising female employment does not imply that mortality will double, and fertility is directly related to the number of children born over time. The wording says “possible,” so it appropriately allows for variation while identifying the most likely effect.

A population pyramid shows the age and sex composition of a population. Its base represents children and the youngest age groups, who are the most recent birth cohorts. When fertility gradually declines, fewer babies are added in each new cohort. Consequently, the width of the base becomes smaller compared with the middle-age groups.

Low mortality also means that more people survive into middle and older ages, so the upper and middle sections may become relatively larger over time. The change is gradual because an existing large child population does not disappear immediately; it grows older as new, smaller cohorts enter at the bottom. Thus the expected change is that the base gradually narrows, making option A correct. The base will not become broader unless fertility rises, and low mortality does not make the upper part disappear.

In the second stage of demographic transition, mortality falls, especially among infants and children, while fertility often remains high for some time. This means that the number of births may still be large, and a greater share of those children survives than before. The population of children can therefore become large even though the mortality rate has declined.

A larger surviving child population increases the need for vaccinations, nutrition programmes, paediatric care, schools, and other child services. Falling mortality does not make children disappear, and zero fertility would have the opposite effect. A sudden rise in the elderly population is also not the main explanation. Thus option A best explains the increased demand.

Low fertility produces smaller groups of children. However, the effect on public services is not immediate, because children born today reach school age only after several years. After this time lag, fewer children may need places in primary schools, so the demand for classrooms, teachers, and new primary-school buildings may slow or decline.

Thus option A is correct. The other services listed mainly serve older people and may face greater demand when the population ages, even while the number of children falls. Lower fertility does not remove every public need; it changes the age composition and therefore changes which services are most required. The exact size of the decline depends on migration and population distribution.

A rapid fall in fertility immediately changes the number of children being born, but it does not instantly change the age structure of the whole population. The smaller groups born after the fertility decline must pass through childhood and adulthood before they can become part of the elderly population. This movement through age groups takes several decades. At the same time, people who are already middle-aged or elderly remain in the population and gradually affect its composition. Consequently, ageing is a gradual demographic process rather than an immediate result.

Option A is correct because age structure reflects the accumulated history of births, deaths, and migration. Low fertility first reduces the young share and may increase the relative share of older groups, but the full effect appears over time. Option B is wrong because low fertility does affect age structure. The choices claiming that elderly people suddenly appear or that mortality always rises confuse separate demographic processes. Ageing can occur even without a sudden rise in mortality.

Natural increase is found by subtracting the death rate from the birth rate. Here the calculation is \(25-25=0\) per thousand, so births and deaths balance and there is no natural increase or natural decrease during that period. However, a rate of 25 per thousand is not extremely low. Therefore, the country cannot be described simply as having very low birth and death rates, even though both rates have fallen from earlier levels.

Option A is the best interpretation: natural increase is zero, while both rates remain moderate. Rapid natural increase would require births to exceed deaths, and natural decline would require deaths to exceed births. Births and deaths have certainly not stopped, because both rates are 25 per thousand. The comparison with earlier rates describes change over time, but it does not alter the current balance between the two rates.

The base of a population pyramid represents younger people, especially children. When fertility remains high, each year brings a large number of births, so many large child cohorts accumulate at the bottom. If mortality, particularly child mortality, falls, more of these children survive. Consequently, the lower part does not narrow quickly and may stay broad for an extended period.

Option A is correct because continued high fertility keeps adding large younger groups, while lower mortality increases their survival. A base cannot immediately become narrow while births remain high. The upper part does not disappear; older groups may gradually expand as survival improves. A rectangular shape would indicate a different age distribution, not the direct result described here.

Low fertility reduces the number of children entering the population, while a rising average age usually indicates that people are living longer and that older groups form a larger share. These changes alter the demands placed on public services. A country may still need child health, childcare, and education services, but it may also need stronger elderly healthcare, long-term care, accessible housing, and sustainable pension arrangements. Planning must therefore respond to the whole age structure rather than focusing only on children.

Option A is correct because it combines continuing child services with greater attention to older people. Expanding only primary schools would not address the needs created by longer lives and a larger elderly share. Reducing health services or ending elderly care would make demographic pressures worse. The exact policy mix depends on national conditions, but the general planning shift toward ageing-related support is clearly justified by the information given.

Demographic Transition Theory identifies stages mainly through long-term patterns of birth rates and death rates. Total population growth is affected not only by natural increase but also by immigration and emigration. Therefore, a country may have a growing population even when families are becoming smaller, simply because more people are entering than leaving. Population density and migration numbers alone cannot identify the demographic stage.

The correct method is to examine whether mortality is high or low and whether fertility is high, falling, or low over time. Immigration should be considered separately when explaining total population change. It may alter the size and age composition of the population, but it does not replace birth-and-death-rate analysis. Hence option A is correct.

When fertility falls, the proportion of children may decline because fewer babies are entering the population. At the same time, large groups born during earlier periods of higher fertility can reach working age. This changes the age structure: a relatively larger share of people may be able to work, while the child dependency burden becomes smaller. That situation creates the possibility of a demographic dividend, meaning faster economic progress if workers are healthy, educated, and productively employed. It also creates a serious requirement for enough jobs, skills, infrastructure, and fair opportunities.

Option A is correct because it states both sides of the situation: an opportunity for a demographic dividend and the need to create employment. The dividend is not automatic; without jobs and suitable policies, a large working-age population may face unemployment or underemployment. The other choices describe only high mortality, child growth, or a return to the first stage, none of which follows from declining fertility and a rising working-age group.

A fall in fertility first reduces the number of young children entering the population. This lowers child dependency. However, the elderly population does not become large immediately, because people born many decades earlier need time to reach old age. During the interval, relatively large generations born before the fertility decline may be concentrated in working ages. As a result, the working-age share can be relatively high, creating a possible demographic-dividend period.

Option A is correct. Option B is too strong because a population does not become aged immediately after fertility falls. Option C reverses the likely effect: lower fertility generally reduces, rather than increases, child dependency. Option D is unsupported because fertility decline does not require high mortality. The exact size of the working-age share depends on past births, survival, migration, and the age boundaries used, but the temporary situation described in option A is demographically plausible.

Natural population growth is determined by the difference between the birth rate and the death rate, ignoring migration. If the death rate is already low and remains so, a fall in the birth rate from 30 to 15 per thousand makes this difference much smaller. For example, if mortality were 8 per thousand, natural growth would fall from 22 to 7 per thousand. The exact new rate depends on the actual mortality value, but the direction is clear: the pace of natural increase slows substantially. Migration could affect total population growth separately, but it is not mentioned here.

Option A is correct because lower fertility narrows the gap between births and deaths. Option B is incorrect because halving the birth rate does not double population growth. Option C ignores the direct effect of the lower birth rate, and option D is not logically necessary: mortality does not have to rise when fertility falls. Thus, the best conclusion is that population growth becomes considerably slower.

The total dependency ratio compares dependent age groups with the working-age population. Children are one dependent group, and older people are another. If fertility falls, the proportion of children usually decreases, so child dependency declines. If the proportion of elderly people remains stable during the same period, the increase in elderly dependency does not offset that fall. Consequently, the total number of dependents relative to working-age people may initially become smaller. This can temporarily create a more favourable age structure.

Option A is correct because total dependency is the combined effect of child and elderly dependency. The word “may” is important: the exact result depends on the sizes of all age groups and on the chosen age definitions. It is not true that total dependency must always rise. Elderly dependency would not immediately double simply because fertility falls, and no change is not required. Over a longer period, population ageing can increase old-age dependency, but under the conditions stated, the initial effect can be a decline in total dependency.

A population pyramid does not show only the babies born in the current year. Its lower age groups contain children born across several earlier years, and each group moves upward as it grows older. If fertility was high in the recent past, those years produced unusually large child cohorts. Even after fertility declines, these children remain in the lower part of the pyramid for several years, so the base may stay broad before it begins to narrow.

Option A is correct because it uses the idea of population momentum and age cohorts. Option B is wrong because fertility strongly shapes the pyramid’s base. Zero mortality is unrealistic and is not required, so C is wrong. Migration of elderly people would affect the upper part much more than the broad child base, so D does not explain the situation.

Low fertility means that fewer children are being added to the population, while high life expectancy means that more people survive to older ages. Over time, this changes the age structure: the share of elderly people grows and the relative share of children declines. Governments may therefore face greater demand for pensions, social-security payments, geriatric health care, medicines, and long-term care. This does not mean that schools, vaccination, or child nutrition become unnecessary, but they are not the main increasing need described by these demographic conditions.

The clues point to population ageing. A country with many older residents must plan for income support after retirement and health services suited to chronic illness and long-term care. The long-run pressure is therefore on pensions and elderly health services, making option A correct. The other choices are too narrow because they focus only on children or one service. Population policy should remain balanced, but the age pattern in the question gives elderly support the clearest priority.

The second stage becomes prolonged when mortality improves before fertility falls. During this interval, many more people are born than die each year, so the natural increase remains high. Repeated high births add successive large groups of children to the population. This creates a broad-based age structure and, after some years, a very large young population. The total population also grows cumulatively because each year’s increase is added to the previous population.

Option A is correct. Immediate population ageing would be more associated with long-term low fertility and longer life expectancy, not with sustained high births. Fertility does not become zero merely because the second stage lasts longer, and natural increase does not end while births remain substantially above deaths. The answer correctly identifies both major effects: rapid cumulative growth and a large youthful population.

Very low fertility tends to make future generations smaller and therefore pushes the population toward ageing. However, a large inflow of young migrants adds people mainly to younger and working-age groups. This can increase the denominator used when considering the elderly share and can strengthen the labor force. As a result, the pace or apparent intensity of ageing may be reduced for some time, although migration does not permanently remove the underlying effect of very low fertility.

Option A is correct because it says ageing may slow temporarily, not that it will disappear. Immediate ending of ageing and a zero elderly population are impossible conclusions: older residents remain present, and migrants themselves age over time. “No effect” is also too strong, since the age composition of migrants can alter the population structure. The exact effect depends on migrants’ ages, numbers, and duration of settlement.