In Certain Areas of the World Where There's a High

In certain areas of the world where there's a high incidence of malaria, there's also a high incidence of sickle-cell anemia. Sickle-cell anemia results from a mutation in the gene that codes for hemoglobin. Malaria is an infectious disease carried by mosquitoes. Both malaria and sickle-cell anemia can be fatal. If an individual is homozygous for normal hemoglobin, they're more prone to malaria. If an individual is homozygous for sickle-cell hemoglobin, they'll develop sickle-cell anemia. However, if an individual is heterozygous and possesses one allele for normal hemoglobin and one allele for sickle-cell hemoglobin, they're less prone to malaria and won't develop sickle-cell disease. This is an example of how

A) being heterozygous can result in greater fitness for an individual.
B) inbreeding depression can result in reduced rates of survival.
C) genetic drift can occur in small populations.
D) homozygous individuals are often unhealthy.