Answer:
B.) Exchange Rate
Step-by-step explanation:
A.) is incorrect because birth rate affects population size. If all other factors are the same, a higher birth rate will increase a population size because more individuals are being introduced into a population. A lower birth rate usually results in the decrease of a population size.
B.) is correct because exchange rate does not affect population size. The rate of exchange between countries has little to no impact on how many individuals live in a particular area.
C.) is incorrect because death rate affects population size. If a death rate is high enough, it can decrease a populaton size. If the death rate is low, fewer individuals are being removed from a polulation, thus keeping the population size relatively stable or increasing (usually).
D.) is incorrect because migration rate affects population size. If the migration rate leans towards more emmigration, more individuals are leaving a population than coming in, thus causing a decrease in the population size. Should a population have have high rates of immigration, the population size usually increases with the influx of individuals.
All of the wrong choices directly describe the flow of individuals in or out of a population. While the correct choice can indirectly affect population size, it is the least significant.