In central Africa, the frequency of the sickle-cell allele has remained stable over the years because the allele protects against malaria. In the United States, malaria was eradicated by eliminating the mosquito that spreads the disease
The decreasing frequency of the sickle-cell allele in African Americans since malaria was eliminated in the United States is an example of
A) stabilizing selection.
B) genetic drift.
C) the founder effect.
D) disruptive selection.
E) directional selection.
E
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