Though Sickle Cell Anemia Is Frequently Lethal for Individuals Who

Multiple Choice

Though sickle cell anemia is frequently lethal for individuals who are homozygous for the sickle cell allele, natural selection seems to have maintained that allele in certain geographic locations.A likely explanation for this observation is

A) the forward mutation rate to sickle cell is much higher in those regions.
B) individuals with sickle cell anemia live longer and have more children.
C) reversion from sickle cell to wild type is prevented in some populations.
D) individuals who are heterozygous for the sickle cell allele are protected from malaria.
E) only certain populations have been tested for the presence of the sickle cell allele.