The Frequency of the Allele That Causes Sickle Cell Disease

Multiple Choice

The frequency of the allele that causes sickle cell disease is higher in some populations than in others because

A) the gene mutates at different frequencies in different parts of the world.
B) the incidence of malaria differs in different parts of the world.
C) sickle cell disease screening is better in developed countries.
D) heterozygotes are resistant to cholera.