Demographic Transition Theory

Demographic Transition Theory studies how birth rates, death rates, and population growth change together as a society develops. Total population growth gives only the final result; it does not show the separate forces producing that result. Therefore, the same growth rate may represent very different demographic situations. Option A is correct because equal or similar growth can result from different combinations of births and deaths. Migration can also affect population, but it is not the main reason for this question.

For example, slow growth may occur when both birth and death rates are high, as in the first stage. It may also occur when both rates are low, as in a later stage. In the first case, many births are almost balanced by many deaths; in the later case, fewer births are balanced by fewer deaths. Thus, examining only total growth can hide the stage of transition and the population’s age structure. Birth and death rates must be studied separately to understand the real demographic process.

Demographic transition is identified by changes in both mortality and fertility. Here the death rate is already low at 9 per thousand, so the major change is a fall in the birth rate from 33 to 25 per thousand. This indicates that fertility decline has begun after the mortality transition has already occurred. Such a pattern represents movement toward the third stage.

Initially, the natural increase is 33 − 9 = 24 per thousand. Later, it becomes 25 − 9 = 16 per thousand. Population is still increasing, but the increase is slowing because the birth-death gap is narrowing. The country is therefore moving from the second stage toward the third stage. It is not returning to the first stage, and mortality transition did not just begin. Option A follows.

Natural increase is the difference between the birth rate and the death rate, while migration is excluded from this calculation. If mortality falls first, fewer people die, but fertility remains high for another ten years. Consequently, the gap between births and deaths becomes wider, and the population grows more rapidly during this interval. Therefore, option A is correct.

For example, if the birth rate remains 35 per thousand while the death rate falls from 30 to 12 per thousand, the natural increase rises from 5 to 23 per thousand. The exact figures are not given in the question, but the direction is clear: births continue at a high level and deaths decrease. Natural increase cannot be zero or negative in this situation, and births and deaths do not become equal merely because mortality declines.

A fall in child mortality means that a larger share of children born will survive. If families still prefer an average of five children, fertility remains relatively high and the reduction in deaths does not immediately lead to fewer births. More children are therefore both born and kept alive. This increases the number and proportion of children and young people in the population. The effect may be especially strong when health improvements occur before family-size preferences change.

Option A is correct because the combination of high fertility and improved child survival can rapidly expand the child and youth population. Birth rates do not immediately become very low merely because children survive better. The elderly cannot become the dominant group immediately from a decline in child deaths, and natural increase does not end while births remain well above deaths. The result describes population momentum in an early demographic-transition setting.

Urbanization and female education usually change the costs, timing, and preferred size of families. In cities, housing, education, and child-rearing can be expensive, while women may study longer, enter paid work, and marry later. Education also improves knowledge of health and contraception. Since mortality is already low, families do not need to have many births to ensure that some children survive.

Together, these conditions generally encourage smaller families and postpone childbearing. Thus the most likely change is a decline in the birth rate, making option A correct. A sharp rise in mortality contradicts the information given. A rise in birth rate is not necessary, and urbanization and education do not cause migration to end completely. The answer describes a likely demographic tendency, not an unavoidable result in every country.

Natural increase is found by subtracting the death rate from the birth rate. Here the calculation is \(39-17=22\) per thousand. This means that, before considering migration, the population increases by 22 persons for every 1,000 people in a year. A high birth rate together with a much lower death rate creates a large positive gap and therefore rapid natural population growth.

Option A is correct because the numerical result is 22 per thousand and the pattern best resembles the second stage of demographic transition. In that stage, mortality falls because of health, sanitation, and medical improvements, while fertility often remains high. The first stage would have both high birth and high death rates, not such a wide gap. The values in the other options either use the wrong calculation or attach the result to an unsuitable stage.

Natural population increase is found by subtracting the death rate from the birth rate, when migration is not being considered. Here the birth rate is 14 per thousand and the death rate is 11 per thousand, so the difference is \(14-11=3\) per thousand. A positive difference means the population is increasing naturally, but a gap of only 3 per thousand represents slow growth. Both rates are also low, which is typical of a later demographic-transition stage.

Option A is therefore the best explanation: both rates are low and the gap between them is small. Option B is incorrect because a death rate of 11 per thousand is not described here as very high. Option C is wrong because a birth rate of 14 per thousand is not very high. Option D cannot be concluded because no migration information is supplied. The calculation directly supports slow natural growth.

The availability of family planning does not automatically produce low fertility. People must be able and willing to use it, and their social expectations about family size also matter. If having many children brings status, respect, security, or approval from relatives and the community, couples may continue to prefer larger families. In that situation, fertility can remain high even when contraceptive information and services exist.

Option A is therefore the reasonable expectation. The other choices confuse fertility with mortality or migration, or make an impossible absolute claim. A birth rate will not immediately become zero merely because family planning is available. Nor must mortality rise when families are large. The question describes a social norm that supports larger families, so a relatively high birth rate is the logical conclusion, though the exact level would depend on other conditions too.

Natural increase is calculated as the birth rate minus the death rate. Initially, the birth rate is 34 per thousand and the death rate is 28 per thousand, so the natural increase is \(34-28=6\) per thousand. After the death rate falls to 12 per thousand, it becomes \(34-12=22\) per thousand. Thus, natural increase changes from 6 to 22 per thousand, which is choice A.

The change is an increase of 16 per thousand, although the option asks for the initial and final values. Births have not changed, but deaths have fallen by 16 per thousand. That reduction widens the gap between births and deaths by the same amount. Options that begin with 22 or 16 confuse the order of calculation or report only the change rather than the two rates.

Natural increase is found by subtracting the death rate from the birth rate: natural increase equals birth rate minus death rate. At first, it is 29 − 7 = 22 per thousand. After the birth rate falls to 18 per thousand, it becomes 18 − 7 = 11 per thousand. Thus natural increase falls by 11 per thousand, from 22 to 11 per thousand. The death rate is unchanged, so only the fall in births changes the result.

This calculation explains why option A is correct. Option C incorrectly repeats the birth rates and does not calculate natural increase, while option D ignores the change in birth rate. The population still has positive natural increase because 18 is greater than 7; it has not become zero or negative. The example illustrates how declining fertility narrows the gap between births and deaths.

A fall in infant mortality shows that public health conditions have improved, but it does not automatically mean that fertility has already declined. If education remains limited, families may still marry earlier, prefer larger families, and have less access to information or services that support lower fertility. Social changes in reproductive behaviour may therefore lag behind health improvements.

This combination—declining mortality with persistently high birth rates—is characteristic of the second stage of demographic transition. The country has moved beyond the first stage because mortality is falling, but it has not yet reached the third stage, where fertility also declines substantially. Therefore option A is the best answer. The evidence does not support a post-transition stage or continued first-stage conditions.

In the first stage of demographic transition, both birth and death rates are high, but the death rate can change sharply from year to year. Epidemics, famine, war, severe disease, or food shortages may suddenly cause many deaths. If deaths temporarily become greater than births, the population will decline during that period, even though the usual birth rate is high.

The other choices do not explain this pattern. Extensive family planning and very small families would mainly reduce births, while a low death rate would not cause population loss in a high-mortality setting. The important idea is that a temporary mortality shock can make the natural increase negative. Therefore, option A correctly identifies epidemics or famine as the explaining factor.

In the demographic transition, the second stage is marked by a high birth rate and a falling death rate. Improvements in food, sanitation, medicine, and health services allow more children to survive, while families may continue to have many births. The difference between births and deaths therefore becomes large, producing rapid natural population growth. A large share of children aged 0 to 14 is consistent with this high-fertility situation.

Option A follows because rapid growth and a broad base in the age structure are typical signs of the second stage. In the third stage, birth rates begin to fall, so growth usually slows and the proportion of children becomes smaller. The first stage has both high birth and high death rates and generally little population growth. The low-fertility stage is not described by rapid growth or a very large child group.

A falling share of children together with a rising share of elderly people shows that the population is becoming older. Fewer births create smaller groups of children, while better survival and longer life expectancy allow more people to reach old age. The age structure therefore shifts away from children and toward older adults.

This process is called population ageing, so option A is correct. Population explosion would imply very rapid population growth, usually linked with high birth rates, not a shrinking child share. A return to the first stage is not a standard explanation for this pattern, and rising infant mortality would not explain a growing elderly proportion. The evidence points to ageing caused by low fertility and improved survival.

When death rates fall while fertility remains high, many babies are born and a much larger share of them survives childhood. This creates a broad base of children and young people in the population. As these cohorts grow, the country develops a youthful age structure, often shown by a population pyramid with a wide lower portion. The effect is not limited to the moment when mortality first declines; continued high fertility keeps adding large young cohorts.

Option A is correct. An immediately aged structure would require low fertility over time and longer survival into older ages, not high fertility. The age structure is affected directly because births and survival determine the sizes of different age groups. Thus, low mortality combined with prolonged high fertility can produce a large dependent child population and a youthful population overall.

Health care and nutrition affect survival directly. Vaccination, medical treatment, clean facilities, and adequate food can reduce deaths, especially among infants and children. These improvements can occur before major changes take place in family behaviour. Urbanisation, education, women’s employment, and access to family planning often influence decisions about the number and timing of children, but their effects may take time.

If urbanisation does not increase and these fertility-changing influences remain limited, families may continue to have relatively many children for some period. Thus mortality may fall while fertility remains high temporarily, producing faster natural increase. Option A is therefore correct. The other options are unreasonable: fertility does not immediately become low merely because health improves, mortality does not rise as a result, and migration is not the only possible change.

Natural increase equals the birth rate minus the death rate. Initially, the birth rate is 26 per thousand and the death rate is 8 per thousand, giving \(26-8=18\) per thousand. After family planning expands, the birth rate falls to 18 per thousand. With mortality still at 8 per thousand, the new natural increase is \(18-8=10\) per thousand.

Thus, choice A is correct: natural increase falls from 18 to 10 per thousand. The change is caused by the reduction in births, while the death rate remains unchanged in the calculation. It would be incorrect to compare the new birth rate directly with the old natural increase, because natural increase must always use birth rate minus death rate for the same period. Family planning lowers fertility and therefore narrows the birth-death gap.

The current birth rate describes births occurring now, whereas the size of the child population also reflects births from earlier years. Children born during several previous years remain in the child-age group for a period of time. Therefore, a country can have many children even after its present fertility rate has started to decline.

If birth rates were high in earlier years, those large birth cohorts will continue to appear as a large child population until they grow older. A lower current rate changes the number of new births, but it cannot instantly remove children who have already been born. The child population is not created only by migration, and mortality is not always zero. Hence, option A provides the correct demographic explanation.

The third stage generally has a low fertility rate, but total births depend on two things: the number of children born per woman and the number of women in reproductive ages. If a country has a very large young population, many people may enter reproductive ages at the same time. Even if each woman has fewer children than earlier generations, the large number of potential parents can keep the total number of births high for several years. This is sometimes linked with population momentum.

Thus, option A is correct because it describes a possible temporary effect, not an unavoidable one. Births do not immediately become zero, and mortality does not have to rise. The population cannot be assumed to decline immediately either, since the large young cohort may continue producing births. Fertility per woman and total births are related but are not identical measures.

Natural increase measures the balance between births and deaths within a population. It does not include migration. The calculation is simple: subtract the death rate from the birth rate. A positive result means births exceed deaths, a negative result means deaths exceed births, and zero means the two rates are equal.

In this case, the calculation is \(20-20=0\) per thousand. Births and deaths therefore balance each other naturally. The correct choice is option A, zero per thousand and natural balance. This does not necessarily mean that the total population cannot change, because immigration or emigration could still alter it; the answer concerns natural increase only.

Natural increase depends on the difference between the crude birth rate and the crude death rate. If both rates are equal, the natural increase is zero, apart from migration. Thus, with birth and death rates of 8 per thousand, the difference is 0 per thousand. The same is true when both rates are 20 per thousand: the difference is also 0 per thousand. However, the two populations are not identical in demographic conditions.

The 8-per-thousand pattern has both low fertility and low mortality and is more consistent with a modern low-rate population, often associated with the later part of demographic transition. The 20-per-thousand pattern has much higher levels of both births and deaths and may represent a different demographic setting. Therefore, option A is the best choice. Options B, C, and D incorrectly treat equal growth as proof that the two situations or stages are identical.

A preference for smaller families tends to reduce fertility, but old-age dependence on children can slow that reduction. In some societies, children are expected to provide income, care, or security when parents become elderly. If pensions and other support are weak, parents may still consider having more children economically useful, even while social attitudes are moving toward smaller families. The two influences therefore work in opposite directions.

The decline will not necessarily stop, and it will not make fertility zero. It may simply be slower than it would be where reliable old-age support exists. The statements that fertility must rise or mortality must double are unrelated and unsupported. Thus, option A correctly describes a relatively slow decline in fertility.

Fertility decisions are influenced by both economic security and social opportunities. A strong pension system can reduce the need for parents to depend on several children for support in old age. At the same time, female education may delay marriage and childbearing, improve knowledge of contraception, and widen opportunities for study and employment. These changes can raise the perceived cost and reduce the economic necessity of having many children.

Together, the two conditions can encourage couples to choose fewer children and invest more in each child. They do not directly cause mortality or infant mortality to rise, and they do not force society to return to large families. The expected demographic change is therefore a decline in the birth rate, making option A correct. The effect is a likely social tendency, not an immediate or universal result in every household.

In the second stage of demographic transition, mortality declines but fertility often remains high. As a result, the number of surviving people can increase rapidly. This creates a need for more food, water, housing, schools, health care, transport, and other public services. If these facilities do not expand as quickly as the population, existing supplies and institutions may become overstretched.

The problem is therefore pressure on resources and services. This may appear as crowded homes, shortages of water or food, pressure on schools and hospitals, or difficulty providing jobs and infrastructure. Population does not immediately decline, because births are still relatively high, and fertility does not become zero. Immediate population ageing is also unlikely because the age structure usually contains many young people. Hence option A is correct.

Natural increase is calculated by subtracting the death rate from the birth rate, with both rates expressed per thousand people. At present, the natural increase is calculated as \(32-7=25\) per thousand. This means births exceed deaths by 25 per thousand people. After the predicted decline, the natural increase would be \(18-7=11\) per thousand.

The later value is still positive, so the population would not immediately begin to decline naturally. However, the gap between births and deaths falls from 25 to 11 per thousand. Therefore, the pace of natural population growth becomes slower. The correct choice is A, natural increase will slow. It will not accelerate or remain unchanged, and it will not become negative unless the birth rate falls below the death rate. Migration could alter total population, but it is not included in this calculation.