Population Growth

Natural increase depends on the difference between the birth rate and the death rate, not on the birth rate alone. The birth rate is 28 per thousand and the death rate is 25 per thousand. Both rates are relatively high, but they are close to each other.

Their difference is \(28-25=3\) per thousand. Thus, the natural increase is only 3 per thousand, or 0.3 percent, assuming the rates refer to the same population and period. Option A correctly identifies the small gap as the reason for limited natural increase. The other choices either deny the role of birth rate, confuse death with migration, or make an unjustified absolute claim.

Natural increase depends on births and deaths, not directly on migration. When health improvements reduce the death rate quickly, fewer people die in each period. If fertility behavior changes only later, the birth rate remains high for some time. The number of births then exceeds the number of deaths by a larger margin than before.

This produces rapid natural increase in the initial decades. Better health may also allow more children to survive, reinforcing the growth of younger age groups, although the immediate question concerns the total natural increase. A negative or stable population would require births to be no greater than deaths, while migration is not the only possible source of change. Therefore option A, natural increase will accelerate, is correct.

Zero net growth only means that the total number of people is not increasing or decreasing through the relevant balance. It does not reveal whether births and deaths are both low, both high, or balanced in some other way. A country with many births and many deaths can have the same net result as a country with very few births and very few deaths, but the demographic processes are much more active in the first country.

Therefore, the first country may have higher demographic turnover: many people enter the population through birth and many leave through death. Its age structure may also differ, but it cannot be identified with certainty from the information given. Option A is correct. Zero growth does not mean that structural change is impossible, and low mortality does not mean that no one dies, so options B, C, and D are unsupported.

The Rule of 70 is a quick estimate for doubling time: doubling time is approximately \(70\) divided by the annual growth rate in percent. It works best when the growth rate remains fairly constant. A result of 25 years therefore represents an estimate based on the current rate, not a guarantee of the actual future period. The correct answer is option C: the actual doubling time is likely to be more than 25 years.

If the rate declines every five years, each later period adds population more slowly than the Rule of 70 assumed. The population will therefore need additional time to reach twice its starting size. The exact delay cannot be calculated without the future rates, so “more than 25 years” is the appropriate qualitative conclusion. It would not be exactly 25 years unless the rate stayed constant, and it certainly would not be zero.

A city receiving many people aged 18 to 24 usually receives students, trainees, and young workers. Their immediate needs are connected with study, employment, and independent living. Therefore, demand is likely to rise for places to stay, affordable rented rooms, transport, colleges or training centres, and beginner-level jobs. These needs appear earlier than needs associated mainly with old age or large families.

Option A is correct because it combines the major services required by this age group. Young people may need hostels near institutions, rental housing near workplaces, reliable buses or other transport, and entry-level employment. Elderly care and pensions mainly serve older populations, while schools for large families do not directly describe the principal demand created by this age structure. The exact order may vary by city, but the broad demographic link is clear.

Births can keep the present child population large, but population structure also depends on which adults remain in the region. People aged 25 to 44 are commonly in important working and family-forming years. If many of them leave, the area loses current workers and a substantial part of the group that could have children locally in the near future.

Therefore the existing number of children may remain high for some time because they were already born, while future births can decline as the number of potential parents falls. The local labor force may also weaken, especially if replacement by other working-age people is limited. The result is not certain in every case, but it is the most likely effect among the choices. Thus option A is correct; the words “always” and “definitely” make options B and C too absolute.

Total population growth has two main components in this calculation: natural increase and net migration. Natural increase is positive when births exceed deaths. Net out-migration is negative because more people leave than enter. The total rate is found by adding the signed rates, not by adding their absolute sizes. Thus opposite signs must be retained in the calculation.

Here the total is \(2.1+(-2.1)=0\) percent. The positive natural increase is exactly cancelled by the negative net migration rate, so the population can remain numerically stable. This does not mean that no births, deaths, arrivals, or departures occurred; it means their combined effect on population size is zero. Therefore, option C is correct, while +4.2 percent incorrectly ignores the negative sign.

The elderly dependency ratio compares the number of older people with the population in the usual working-age range. It is a ratio, not simply a count of the total population. Therefore, the total population may remain almost unchanged while the ratio rises if older people become a larger share or if the working-age group becomes smaller. This can happen through low fertility, longer survival, or age-selective migration.

Choice A is correct because it describes the essential relationship: the elderly population is growing faster relative to the working-age population. A high birth rate would generally increase the younger share, not directly explain a rapidly rising elderly ratio. A doubling total population is not stated and would not by itself determine the ratio. Choice D is also wrong because migration can alter age structure.

Per-person availability is found by comparing the total amount with the number of people sharing it. Here, energy production rises by 12 percent, while population rises by only 8 percent. Since the supply grows faster than the population, the amount available on average for each person increases, assuming other relevant conditions remain broadly unchanged.

A simple index calculation makes this clear. Start with production of 100 units and a population of 100 people, giving 1 unit per person. After the changes, production is 112 units and population is 108 people. The new average is approximately \(112/108\), which is greater than 1. Therefore option B follows. This does not mean everyone receives equal energy or that shortages disappear; it describes the average availability.

Sewage-treatment capacity must be compared with the amount of wastewater produced. Here, population increases by 13 percent, but treatment capacity increases by only 4 percent. If people continue to produce roughly the same amount of wastewater per person, the total load grows much faster than the system’s ability to treat it. Per-person capacity therefore falls, even though the absolute capacity has increased.

Option A follows directly from this imbalance. More pressure may produce overloading, untreated discharge, overflow, or poorer treatment, although the exact outcome depends on water use, infrastructure, and management. Option B is opposite to the likely effect, C incorrectly assumes population growth reduces waste, and D ignores the direct relationship between population, wastewater generation, and treatment demand. Thus A is the best choice.

A population’s total growth rate describes the current balance of births, deaths, and migration. It does not immediately determine the size of every age group, because age groups are formed from people born in earlier years. The 25–54 group over the next 12 years may therefore include large cohorts born during an earlier period of higher fertility, even if present growth has begun to decline.

Option A is correct because these larger earlier cohorts gradually move into the specified adult ages. Age structure has momentum: past birth patterns continue to influence the population for decades. Option B is too absolute, since a falling total growth rate does not make every age group fall at once. C is incorrect because adult cohorts are strongly linked to past births, and D is unsupported because migration need not be zero. Hence A best explains the situation.

Population growth is not determined by one number or one rate. It results from births, deaths, and migration, while the age structure shows how many people are likely to enter childbearing or working ages. Cohorts and time series help us follow groups through time and identify whether change is temporary or lasting. Absolute change shows how many people were added, whereas rates allow fair comparison between places of different sizes.

Therefore, option A is the most complete combination. It connects the main causes of growth with the evidence needed to project its future direction. Total population alone, birth rate with land area, or annual growth alone would omit important processes and could give a misleading picture. This integrated approach is appropriate for expert analysis.