Which of the following statements best predicts what would happen in response to a prolonged epidemic of malaria in a population with no previous exposure to malaria?

The frequency of the sickle-cell allele (s) would increase.

Explanation:

Because both those affected by sickle-cell disease and carriers who possess only one sickle-cell allele are much more resistant to malaria, these two genotypes would be selected for during a prolonged epidemic of the illness. Since the homozygous dominant genotype (SS) would be the most susceptible to death from malaria, those with Ss and ss genotypes would be more likely to reproduce and pass their genes on to the next generation. This means that, over time, the frequency of the sickle-cell allele (s) would increase.

Such a scenario has been used to explain the continued existence of the sickle-cell gene in many parts of Africa, where malaria is still widespread and rates of sickle-cell disease are much higher than other areas of the world. In the absence of malaria, however, the sickle-cell gene would be purely disadvantageous and, in any given population, would eventually cease to exist. (got it right on study island)