Demographic Transition Theory

Natural increase is calculated as the birth rate minus the death rate. At the first point, it is \(41-27=14\) per thousand. At the later point, it is \(29-13=16\) per thousand. Thus, although the birth rate fell by 12 per thousand, the death rate fell by 14 per thousand. Because mortality declined by two more points than births, the difference between births and deaths became larger by two per thousand.

Therefore, option A is correct: natural increase changed from 14 to 16 per thousand. The figures 68 and 42 result from adding the two rates, not subtracting them, so they do not measure natural increase. Options B and D use incorrect arithmetic or compare the wrong rates. This example also shows why looking only at the direction of the birth-rate change can be misleading; natural increase depends on both births and deaths together.

When mortality falls quickly but fertility remains high, many more children survive than before. For the seven-year interval, the number of births stays high while the number of deaths has already declined. The difference between births and deaths therefore becomes large, producing rapid natural increase. These surviving children form a large young cohort that will later enter schools, then the labour force, and eventually older age groups. Thus, option A gives the most important immediate demographic effect.

The situation cannot produce an immediate natural decline because births still exceed deaths. It also does not cause immediate ageing, since the largest new group consists of children. Births and deaths are not balanced during the lag; their gap is precisely what drives rapid growth. The later fall in fertility may eventually slow population growth, but it does not remove the effect of the seven-year interval. The age structure created during this period can influence society for many decades.

A birth rate of 30 per thousand and a death rate of 8 per thousand show that births greatly exceed deaths. This is typical of a phase in which mortality has already fallen but fertility remains relatively high, so natural increase is substantial. The rapidly rising average age at marriage adds an important clue about future fertility behaviour.

When people marry later, the average period in which they may have children becomes shorter. Later marriage can also be associated with delayed childbearing, smaller desired families, education, and greater use of family planning. These influences generally make a gradual decline in fertility more likely. They do not make mortality suddenly rise, make natural increase immediately zero, or return the country to the first stage. Thus, choice A follows.

Population age groups are shaped by birth cohorts, not only by the fertility rate of the current year. If many children were born during earlier years of high fertility, that large cohort does not disappear when fertility begins to decline. As its members grow, they continue to enter school age over several years. Thus the number of school-age children can keep rising temporarily even while the number of new births is falling.

Option A correctly describes this time lag. Lower fertility reduces the size of younger cohorts later, but it cannot immediately remove children who have already been born. Mortality being zero is neither necessary nor realistic, so C is not a valid explanation. School-age population is closely related to births in previous years, which makes D false. The pattern is an example of population momentum and cohort effects.

Natural increase equals the birth rate minus the death rate. Here it is \(12-10=2\) per thousand, so the population is still increasing naturally, but only very slowly. The fact that the average age is rising suggests that births are low and people are living longer, producing an older age structure. This combination is consistent with population ageing alongside slow positive growth. The figures alone do not describe a population explosion or a natural decline, although migration could change the total population separately.

Option A is correct because it combines the two clues: the positive difference of 2 per thousand indicates slow positive growth, while the rising average age indicates ageing. Option B is wrong because rapid growth would require a much larger birth–death gap. Option C is wrong because the first stage has high birth and death rates. Option D is wrong because natural decline requires deaths to exceed births, whereas 12 is greater than 10. Therefore, A is the best interpretation.

Very low infant mortality means that most babies survive their early years. Therefore, continued high fertility is less likely to be mainly a response to fear that many children will die. When survival is secure but families still have many children, social and cultural preferences for larger families are a more plausible explanation.

Such preferences can be influenced by traditions, family expectations, the economic value of children, limited access to contraception, or the desire for larger kin networks. The question asks for the most likely explanation, not an explanation that must apply in every society. Severe uncertainty about survival and extremely high mortality contradict the stated condition, while lack of medical facilities is also not supported by very low infant mortality. Hence option A is correct.

Natural increase is calculated as the birth rate minus the death rate. Initially, it is 34 − 14 = 20 per thousand. After the changes, the birth rate is 20 and the death rate is 9, so natural increase is 20 − 9 = 11 per thousand. Therefore, natural increase falls from 20 to 11 per thousand, a decrease of 9 per thousand. The separate declines in births and deaths must not be added together as rates of natural increase.

Option A is therefore correct. Option C adds the birth and death rates, giving 48 and 29, but addition does not measure natural increase. Option D merely describes the fall in death rate and ignores births. Although the death rate also decreases by 5 per thousand, the birth rate decreases by 14 per thousand, so the birth-death gap becomes smaller overall. This is consistent with slowing population growth.

A fall in fertility can reduce the proportion of children and increase the share of people in the working-age group. This creates a possible demographic dividend, but the larger working-age share is only an opportunity, not an automatic economic gain. If women do not enter or remain in paid work, a substantial part of the potential labour force may not contribute fully to production, income, tax revenue, or innovation. Other barriers, such as discrimination, unpaid care, or lack of skills, may also matter.

Thus, low fertility alone does not guarantee a dividend. The dividend is stronger when employment, education, health, gender equality, and productive investment allow working-age people to participate effectively. Low fertility does not eliminate the dividend, female participation clearly has economic relevance, and elderly dependency does not immediately become zero. Option A is correct.

Natural increase is calculated by subtracting the death rate from the birth rate. Here it is \(8-11=-3\) per thousand, so the country has a natural decrease: deaths exceed births by three per thousand people. This calculation does not include migration. Migration is a separate component of population change.

If many young migrants enter the country, their numbers can be larger than the natural loss. Total population may therefore rise even while natural change remains negative. Because the migrants are young, the working-age population may also grow, helping to support employment and economic activity. Migration does not make natural increase positive; it affects the total change separately. Thus, option A is correct.

The second stage of demographic transition occurs when mortality has fallen but fertility remains high. This creates a wide gap between births and deaths, leading to rapid natural increase. If fertility drops sharply only three years later, the high birth rate does not continue for a long period after mortality falls. Consequently, the period during which the country has both low mortality and high fertility is brief, so the second stage is relatively short.

Option A states the essential reason: the birth-death gap will not remain wide for long. Mortality does not need to rise again, so B is irrelevant. Fertility is directly related to the size of natural increase, making C incorrect. Natural increase is not always zero; it is positive when births exceed deaths and negative when deaths exceed births. The short duration follows from the rapid fertility transition.

A demographic dividend is not created merely because the number of dependent children begins to fall. It becomes possible when a relatively large share of the population reaches working age, while the shares of children and older dependants are manageable. The age structure changes gradually because existing children must grow through adolescence before entering the labor force.

Thus, lower fertility can reduce child dependency first, but the working-age population will increase only later. The country also needs education, health, employment, and suitable economic policies to turn this age structure into a dividend. Lower child dependency does not automatically create an immediate benefit, and working-age groups are strongly connected with past birth patterns. Therefore, option A is correct.

This is not a contradiction because population growth and population ageing describe different features. The crude birth rate is 19 per thousand and the crude death rate is 7 per thousand, so natural increase is \(19-7=12\) per thousand, which is positive. The population can therefore continue to grow. At the same time, earlier declines in fertility may produce smaller younger cohorts, while better survival allows more people to reach older ages.

Consequently, the number or share of elderly people can rise even while births exceed deaths, making option A correct. Ageing refers mainly to the changing age composition, not necessarily to a declining total population. Migration and the size of earlier cohorts can also affect the result. Option D reverses the stated figures: the death rate is 7, not greater than the birth rate of 19.

The total dependency ratio combines children and older people relative to the working-age population. Low fertility usually means fewer children, so it tends to reduce child dependency after some time. If the total ratio is nevertheless very high, a large elderly population is the most likely explanation. This may result from long life expectancy, sustained low fertility, or both.

The age structure can therefore be top-heavy even when few children are being born. A country may have many older people compared with the number of workers, making the total burden high. Low fertility does not make dependency zero, because elderly dependency can rise as the population ages. Choice A is correct. The other options either assume high child dependency without evidence or confuse a low birth rate with a large working-age share.

Natural increase is calculated as the crude birth rate minus the crude death rate. Initially, it is \(36-20=16\) per thousand. After the changes, it is \(24-8=16\) per thousand. Although both rates fall, they fall by the same amount: birth rate decreases by 12 and death rate decreases by 12.

Because the difference between births and deaths remains unchanged, natural increase stays at 16 per thousand. Therefore, option A is correct. The calculation is about natural increase only; migration is not provided and cannot be included. A common mistake is to compare the new birth rate alone with the old one, but population growth depends on the gap between birth and death rates.

Both countries have the same natural increase because each has a birth-death difference of 10 per thousand: \(40-30=10\) and \(18-8=10\). However, equal natural increase does not mean that the countries have the same demographic conditions. The first country has both very high birth and death rates, while the second has much lower rates. Their health conditions, age structures, life expectancy, and positions in demographic transition may therefore differ.

Option A is correct because the same growth rate can occur at different combinations of birth and death rates. The first pattern may resemble an early stage or a high-rate transition situation, whereas the second reflects lower mortality and fertility. We should not label the first automatically as stage three or the second as stage one. Natural increase alone is insufficient for identifying a transition stage; both component rates and broader demographic evidence must be examined.

Fertility and housing demand do not move in a perfectly direct way. Lower fertility can reduce the average number of people in each household, but the number of households can still grow. Young adults may leave their parents’ homes, couples may establish independent homes after marriage, and urbanization may create demand for separate apartments. A growing number of smaller households can therefore require more total dwelling units even when fewer children are being born.

Option A is correct because it identifies this household-formation effect. Housing demand depends not only on the number of children but also on household size, living arrangements, income, migration, and urban growth. Mortality becoming zero is unrealistic and would not by itself explain the pattern. The claim that low fertility always reduces housing demand ignores the difference between population size and the number of households.

Pensions and many services for older people are mainly financed through taxes and contributions from the working-age population. Pressure on the tax base becomes greater when the number of workers is not growing fast enough to support the number of elderly people receiving pensions and health care. In that situation, each worker or taxpayer may indirectly support a larger dependent elderly population, unless productivity, savings, taxes, or other funding sources compensate for the difference.

Option A is correct because a slowly growing or declining working-age population makes the ratio of workers to elderly dependants less favourable. Low child dependency alone does not solve this issue. Rapid productivity growth can reduce pressure by raising output and tax revenue, while an inflow of young migrants can enlarge the workforce. Those choices would generally ease, not intensify, the pressure. The greatest pressure occurs when elderly numbers rise faster than the working-age tax base.

Natural increase is determined by the gap between the birth rate and the death rate. A fall in mortality alone could make this gap wider, but a simultaneous fall in fertility reduces the birth rate as well. If both rates decline at a similar pace, the difference between them may change only slightly. Longer life expectancy does not itself determine the number of births.

Thus option A is correct: the birth-death gap will not widen greatly, so natural growth will not become very rapid merely because people live longer. Option B confuses survival with fertility, option C reverses the usual effect of lower mortality, and option D incorrectly replaces natural increase with migration. Migration is separate from the birth-death calculation.

The total dependency burden is related to the number of children and older people compared with the working-age population. If both child dependency and elderly dependency are low, relatively few people require support from each working-age person. This usually means that a large proportion of the population is in the working ages. Such an age structure can create a demographic dividend because more people may be available for employment and production.

However, the dividend is only potential: it depends on education, health, suitable jobs, and effective economic policies. The condition does not describe the high mortality of the first stage, a very large child population, or high total dependency. Therefore option A is the most favorable demographic condition. The answer concerns age composition, not a guarantee that every working-age person will be employed.

Natural increase is the birth rate minus the death rate. At present, the rates are 22 and 7 per thousand, so the present increase is \(22-7=15\) per thousand. If the death rate remains 7 per thousand while the birth rate falls to 14 per thousand, the new calculation becomes \(14-7=7\) per thousand.

The fall in births reduces the gap between births and deaths from 15 to 7 per thousand. Growth therefore continues to be positive, but it becomes much slower. The answer is not 15, because that is the current increase before fertility falls. It is not 14, because the birth rate itself is not the natural increase, and it is not 21. Hence option A, 7 per thousand, follows directly from the stated assumption that mortality stays at 7.

A decline in fertility first produces smaller new child cohorts. After several years, this can reduce the number of children entering primary school, so primary-school demand may fall. However, the age structure does not change all at once. Larger groups born when fertility was higher may still be moving through adolescence and the years before full employment. These young people can increase demand for technical, vocational, or skill-based training. Thus, different age groups can create opposite demands at the same time.

Option A best captures this combination: smaller child cohorts alongside larger pre-working-age youth cohorts. The wording does not mean that every youth cohort must be larger; it describes a likely transitional pattern when earlier births produced a large group. Option B contradicts the stated fertility decline, and option C is too exclusive because the elderly are not necessarily the only growing group. Option D ignores normal differences in cohort size.

Low fertility tends to reduce the number of children entering the population, while low mortality and longer survival increase the share of older people over time. These forces normally encourage population ageing. However, migration changes the age composition as well as the total size of a population. If most immigrants are young adults, the working-age group becomes larger and the proportion of elderly people can temporarily fall or rise more slowly.

This is why choice A is the best answer. The effect is temporary or relative, not a complete reversal of ageing. Young migrants do not make the elderly population disappear, and they do not remove the long-term effect of low fertility. Options B and C are absolute claims, while D incorrectly says low fertility has no effect.

A fall in fertility immediately reduces the share and number of children, but it does not necessarily reduce the total population at once. If a country previously had many births, it may still contain a large group of people in reproductive ages. Even with low fertility per person, this large group can produce a substantial number of births for some time. This is demographic momentum.

At the same time, longer life expectancy means people survive to older ages and deaths may remain relatively low. Continued births plus fewer deaths can keep total population growing temporarily, even while the child population declines. High infant mortality or low life expectancy would work in the opposite direction. Therefore, the combined explanation in option A is the most suitable.

Natural increase equals the birth rate minus the death rate. The starting birth rate is 15 per thousand, and it falls by 1 per thousand each year. Over nine years, the total fall is \(9\times1=9\) per thousand, so the birth rate becomes \(15-9=6\) per thousand. The death rate remains 6 per thousand. Hence, after nine years, natural increase is \(6-6=0\) per thousand.

Option A is correct. The calculation assumes that “after nine years” means nine annual declines have occurred, including the stated change for each year. A result of 3 would follow from a different time interval, not from the conditions given. Zero does not mean that births and deaths have stopped; it means they are equal in rate, so there is no natural increase or decrease before migration is considered.

A rise in fertility creates more births immediately or within the relevant birth period. Babies and young children therefore become more numerous first, increasing the share or size of the 0–14 age group. This is the first direct effect visible in an age pyramid. The new children cannot enter the working-age group immediately, because they must pass through childhood and adolescence. They will affect working-age numbers only after many years, and their effect on the elderly group would take even longer.

Option A is correct because it identifies the child age group as the earliest place where the change appears. The effect will not occur in all age groups at once: older cohorts were born before the fertility increase and are not changed by it. A sudden rise in fertility also does not instantly enlarge the working-age or elderly population. Over time, the larger child cohorts will move upward through the age structure, but the initial visible impact is at the base of the pyramid.