The Persistence of the Sickle-Cell Anemia Allele in Some African

Multiple Choice

The persistence of the sickle-cell anemia allele in some African populations is the result of ____.  

A) a high rate of mutation of the normal allele to the sickle-cell anemia allele
B) the advantage conferred by the heterozygous form when malaria is prevalent
C) nonrandom mating
D) a decline in the occurrence of malaria in Africa
E) genetic drift