59. Demographers use graphs like this one to analyze patterns of population growth and decline.

The graph plots birthrate and death rate over time, in years. In Stage I, both rates begin relatively high. In Stage II, birth rate remains high while death rate decreases. At the end of Stage II and into Stage III, birthrate decreases to match the low death rate.

Suzie studies the graph and concludes that in Stage I and at the end of Stage III, the population of a country either is not changing size or is increasing slightly. Which assumption is necessary for Suzie’s conclusion to be accurate?

A. The population of the country did not increase substantially during Stage II.
B. The population of the country increased at least slightly during Stage II.
C. The population has a roughly equal distribution of people in age groups from ages 0 to 60 years.
D. The difference between the rates of immigration and emigration is insignificantly small.

D. The difference between the rates of immigration and emigration is insignificantly small.

Explanation:

In order for the conclusion of Suzie to be accurate, the difference between the rates of immigration and emigration must be balanced or insignificantly small.

The size of a population is dependent on three factors namely:

When birth rate balances death rate, migration becomes an important factor in determining whether a population will increase in size or otherwise. When immigration rate is more than emigration rate, the population will increase; when emigration is more than immigration, the population will decrease.

In order for the population for the population size to remain relatively constant, the difference between emigration and immigration must be insignificantly small.

The correct option is D.

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