Demographic Transition Theory

When both birth and death rates are low, the country is in a later part of demographic transition. The important point is not merely that both rates are low, but that births are still slightly more numerous than deaths. This creates a small positive natural increase. The population therefore has the potential to continue growing, but its growth will be slow rather than rapid.

For example, if the birth rate is 12 per thousand and the death rate is 10 per thousand, the natural increase is only 2 per thousand. It is positive because births exceed deaths, but the difference is small. A rapid increase would require a much larger gap, while decline would require deaths to exceed births. Thus, choice A correctly describes the likely result.

Fertility decisions are influenced by the costs and benefits of having children. In an agrarian or traditional economy, children may contribute labour or provide support to parents, making larger families economically useful. When that usefulness declines, while education, healthcare, housing, and daily care become more expensive, the financial cost of each child becomes more important to families.

As a result, many families may prefer fewer children and invest more resources in each child. This is a likely tendency, not an unavoidable rule for every household, so the wording “may increase” is appropriate. Option A is correct. A rising birth rate is not necessary, mortality is a separate demographic measure, and saying there will be no effect ignores the influence of changing economic conditions on fertility choices.

Natural increase is calculated by subtracting the death rate from the birth rate. At first, the country has a natural increase of \(37-11=26\) per thousand. Later, the birth rate becomes 27 per thousand while the death rate remains 11 per thousand, so natural increase becomes \(27-11=16\) per thousand. The rate is therefore lower than before.

The correct choice is A: natural increase is slowing. The birth rate has fallen by 10 per thousand, while mortality has not changed. Consequently, the gap between births and deaths has narrowed from 26 to 16 per thousand. This example mainly shows a fertility decline and a slower population increase. It does not show the country returning to the first stage, and it does not indicate that a new mortality decline has begun.

Natural increase is found by subtracting the death rate from the birth rate. Here the birth rate is 28 per thousand and the death rate is 27 per thousand, so the difference is only 1 per thousand. This means that births exceed deaths by a very small amount, producing low natural growth even though both rates themselves are high.

That combination is characteristic of the first or pre-transition stage of demographic transition. In this stage, high fertility is balanced by high mortality, so population growth remains small. The second stage normally has a high birth rate but a substantially lower death rate, producing rapid growth. The third and advanced low-mortality stages generally have lower death rates and usually lower fertility. Therefore, option A is the best answer.

The birth rate is 24 per thousand and the death rate is 7 per thousand. The natural increase is therefore approximately \(24-7=17\) per thousand people per year, assuming the rates are measured for the same period. A low death rate together with a still fairly high birth rate produces a large positive gap. This pattern is characteristic of the second stage, when mortality has fallen but fertility has not yet declined fully.

Option A is therefore the best answer. The first stage normally has high mortality, so a death rate of 7 per thousand does not fit it well. Complete stability in the third stage would involve a much smaller gap between births and deaths, while “high-mortality stage” directly conflicts with the given death rate. The figures indicate rapid natural population growth, not population stability.

Natural population increase is determined mainly by the difference between the birth rate and the death rate, before considering migration. Here the birth rate is 15 per thousand and the death rate is 10 per thousand. The natural increase is therefore \(15-10=5\) per thousand. A difference of only five per thousand means that the population is increasing, but slowly. The death rate is not very high, and the birth rate is not very high either. Also, nothing in the data proves that migration is negative, so that option cannot be selected.

The calculation gives the decisive clue. For every 1,000 people, there are about 15 births and 10 deaths, leaving a natural addition of about 5 people. If the gap were much wider, growth would be faster; if births and deaths were equal, natural growth would be zero. Thus, the small gap between the two rates is the main reason for slow growth. Option A is correct, while option B incorrectly describes the death rate as very high.

In the second stage of demographic transition, death rates fall while birth rates remain high or decline only slowly. As a result, many children are born and more of them survive. These children form a large age cohort. A cohort means a group of people born around the same period, and its size affects the population structure for many years.

When this large group grows up, many members may enter working age at about the same time. The labour force can therefore expand rapidly in the future. This effect is not automatic employment or guaranteed prosperity: education, skills, health, and available jobs determine the outcome. Still, the likely demographic effect described in the question is that large young cohorts later enter the labour force, so option A follows.

When fertility falls, each new generation contains fewer children than the generation before it. At first, the total population may still contain many children because earlier high-fertility cohorts are alive. Over time, however, the smaller new cohorts make children and young people a smaller share of the total population. Longer survival can also increase the number and share of older people, reinforcing the change in age structure.

Thus option A is correct: the share of the young population may decline. The word “may” allows for differences in timing caused by migration, past fertility, and mortality. Young people will not always increase, and a middle-aged group does not simply disappear. Likewise, low fertility does not make the elderly population zero; it may eventually raise its relative share as the population ages.

Family planning can be physically available without being widely used. People’s reproductive decisions are influenced by social approval, cultural and religious beliefs, gender roles, trust, family expectations, and the perceived advantages of having a large family. If these barriers remain, access alone may not produce a rapid fall in fertility.

Consequently, the birth rate may remain high, making option A correct. It cannot be concluded that the rate will immediately become zero; such a change is unrealistic and is not implied by access to contraception. The situation also gives no necessary information about mortality or migration. The question tests the difference between availability of a service and its social acceptance and use.

Social security can reduce the economic reason for having many children. In a society with reliable pensions, insurance, and public support, parents may feel less need to depend on children for income, care, or security in old age. This can make a smaller family a practical choice, especially when education and child-rearing are costly. The correct choice is A. Stronger social security does not directly make mortality rise, end education, or automatically increase births.

This is a broad demographic relationship, not an absolute rule that applies equally everywhere. Fertility is also influenced by culture, income, women’s education, employment, housing, and access to health services. However, when old-age support no longer depends mainly on having several children, the economic benefit of a large family becomes smaller. Thus, improved social protection can contribute to lower fertility over time.

A very youthful age structure means that children and adolescents form a large share of the total population. In the second stage, birth rates remain high, while improvements in health and sanitation reduce infant and child mortality. Many children are therefore born and survive, creating a broad base in the population pyramid.

The first stage also has high fertility, but very high mortality prevents as many children from surviving and may keep population growth limited. In the third stage, fertility begins to decline, so younger cohorts become relatively smaller. Thus, the second stage is the most likely stage for a very youthful age structure, making option A correct. The word “most” is important because age structures can vary among countries.

In the third stage, families have fewer children, so children form a smaller share of the total population. At the same time, mortality is low and people often live longer because health care, nutrition, sanitation, and living conditions improve. Over time, more people survive into older ages while fewer young people are added. Consequently, the proportion of elderly people rises. The correct choice is A. High births and high deaths describe an earlier stage, not the usual third-stage pattern.

This does not mean every person becomes elderly or that all young people leave the country. It means the age composition gradually changes. Smaller younger cohorts and longer lives increase the relative weight of older cohorts. The process may be slow because population age structures change over decades, but its direction is clear when low fertility continues and life expectancy remains high. Planning must therefore include health care, pensions, and support for older adults.

When the death rate falls while the birth rate remains high, the number of births is much greater than the number of deaths. This creates rapid natural increase and causes the total population to expand quickly. Resource planning must therefore prepare for rising demand for food, clean water, housing, schools, hospitals, transport, sanitation, and employment. If facilities do not grow at a similar pace, overcrowding and shortages may develop.

Option A is correct because rapid population growth directly increases the number of people needing public and household services. Options B, C, and D describe the opposite of the likely effect or an impossible result. Lower mortality does not remove the need for schools or water; it usually means more people survive and continue to require these resources.

A fall in fertility changes the number of babies being born now; it does not remove children who were born earlier. If fertility was high in previous years, those years produced large child cohorts. These children remain part of the child population until they grow into older age groups. Consequently, the child population may stay large for some time even after fertility starts to decline. This is a lag caused by age structure and population momentum.

Option A is correct because it links the present child population with earlier high fertility. Option B is wrong because a lower birth rate cannot immediately erase existing children. A zero death rate is neither necessary nor realistic, so C is incorrect. Positive migration might affect population size in some situations, but it is not the most appropriate general explanation here; therefore D is also wrong.

Urbanization can influence fertility, but it is only one part of a larger social process. City life may increase housing and child-rearing costs and may encourage smaller families. However, fertility decisions are also affected by women’s education, employment, access to family planning, age at marriage, income, cultural expectations, and the ability to participate in household decisions. If urbanization grows without progress in female education, some important influences on fertility may remain unchanged.

Option A is correct because the social factors that support smaller families have not all developed equally. Urban residence alone does not guarantee a rapid fertility decline. For example, if women have limited schooling, employment, or decision-making power, families may continue to prefer more children even in cities. The other choices use absolute or incorrect claims: urbanization does not always raise fertility, mortality does not determine fertility by itself, and education does have an important relationship with family size.

The third stage is marked by falling fertility, greater urbanisation, improved education, and changing economic expectations. Families increasingly recognise that raising children requires substantial spending on schooling, health care, nutrition, and future opportunities. When the desired number of children becomes smaller, parents may devote more resources to each child. In this situation, the quality of children’s education, health, and skills can become more important than simply having many children.

Therefore, option C, the third stage, is correct. The first stage has high birth and death rates, while the second stage usually has high births and falling deaths, so large families may still be common. “High-mortality stage” describes a condition rather than the relevant later transition stage. The question focuses on economic development changing family priorities, which is most consistent with the third stage and its movement toward lower fertility.

Natural increase is the difference between the birth rate and the death rate. In this case it falls from 20 to 8 per thousand because fertility, or the birth rate, is declining, while the death rate remains low. This means the population is moving away from the rapid-growth pattern of the second stage toward the slower-growth pattern of the third stage.

Option A is therefore correct. A return to the first stage would require both birth and death rates to become high, which is not stated. A mortality crisis would imply a sharp rise in deaths, also contrary to the information. The change is not merely a migration change because the question specifically identifies falling fertility as the cause. Declining births with already low mortality is the expected direction toward the third stage.

Natural increase is determined mainly by the difference between the birth rate and the death rate. When mortality is already very low but the birth rate remains as high as 30 per thousand, many more people are being added than removed through deaths. This creates rapid population growth, especially if migration does not offset it.

Option A is therefore correct. Fast growth can place pressure on schools, hospitals, housing, water supply, transport, food systems, and employment. Immediate ageing is not the most likely result because a high birth rate produces many children. School demand would rise rather than disappear, and water demand would usually increase with a larger population. The situation commonly resembles an earlier or middle transition phase.

When births and deaths are both low, a growing elderly share usually reflects low fertility combined with longer survival. Fewer children are added to the population, while many adults live into old age. This changes the age structure and increases the number of people who may need pensions, regular medical treatment, medicines, and long-term care. The correct choice is A. A low-birth population does not automatically make primary-school demand double, and mortality does not immediately become high.

The effect is long term because age groups move through life gradually. A smaller child population may eventually reduce the need for some schools, while the older population creates continuing demand for health and social services. The exact pressure depends on life expectancy, migration, public policy, and the size of earlier cohorts. Nevertheless, rising old-age support and health-care needs are the most direct likely consequences described by the situation.

Demographic momentum means that population growth can continue even after families begin choosing fewer children. If earlier generations had high fertility, they may have produced a very large group of young people. When this group reaches reproductive age, many people may have children at roughly the same time. Even if each person has a smaller family than before, the large number of potential parents can keep the total number of births high.

This makes option A possible. Option B is false because small families generally reduce, rather than automatically increase, population growth. If deaths exceeded births, the population would tend to decline, so C does not explain rapid growth. If births had completely stopped, population growth could not continue through new births, making D impossible as an explanation. The key is the age structure created by past fertility.

The second stage of demographic transition begins when mortality falls but fertility remains high. Improvements such as safe drinking water and vaccination prevent many deaths and reduce the death rate. If families continue to have roughly the same number of children, the birth rate does not fall at the same time. This creates a large positive gap between births and deaths.

That gap produces rapid natural population growth, which is the defining pattern of the second stage. The first stage has both high birth and high death rates, while the third stage involves a declining birth rate. A post-transition stable stage has both rates low and usually a much smaller difference between them. Therefore option B is the clearest match.

Natural increase is determined by the difference between the birth rate and the death rate. When family planning becomes more common, couples generally have fewer children, so the birth rate declines. If the death rate is already low and remains stable, fewer births make the difference between births and deaths smaller. The population can still grow, but it grows more slowly.

Option A is correct. The change does not accelerate natural increase, because that would require births to rise relative to deaths. It is also incorrect to say that there is no effect: a lower birth rate directly reduces the natural-increase rate. Mortality does not have to rise; it can remain low while natural growth slows. This pattern commonly represents the movement from a high-growth phase toward a later transition stage.

The first and third stages of demographic transition can both show slow population growth because their high birth and death rates may nearly balance each other. However, the levels of the two rates are very different. In the first stage, both fertility and mortality are high. Frequent deaths, including high infant mortality, offset the large number of births, so growth remains limited.

In the third stage, both rates are low. Better health and living conditions have reduced mortality, while education, urbanisation, contraception, and changing family preferences have reduced fertility. The balance may again produce slow growth, but it occurs at low rates rather than high rates. Therefore option A correctly distinguishes the stages. The other choices either make false absolute claims or ignore the role of birth and death rates.

Natural increase means the number of births minus the number of deaths, without considering migration. When the death rate falls first, fewer people die, while the birth rate remains high. During the 15-year interval, births therefore continue to greatly exceed deaths. The population grows rapidly, so the correct answer is rapid natural increase, choice A.

The interval is often called the expanding phase of demographic transition. It does not mean that the population remains stable or immediately becomes negative. Migration may affect the total population, but it is not the main process described here. The decisive calculation is the positive gap between a still-high birth rate and a newly lower death rate; this gap produces fast natural growth.

When fertility declines, fewer children are born in each new generation, so the share of children in the total population becomes smaller. At the same time, improvements in nutrition, healthcare, sanitation, and living conditions can help people survive to older ages. Consequently, older people form an increasing proportion of the population. This long-term change in the age composition is called population ageing. It is often associated with advanced stages of demographic transition.

The correct choice is A. Population explosion would require rapid growth, usually because births remain high while deaths fall. Returning to the first stage would mean a return to high birth and death rates, not a growing elderly share. High infant mortality would reduce the number surviving from infancy and does not explain a sustained rise in the elderly proportion. Thus, declining fertility combined with longer survival indicates ageing.