Sickle cell anemia is a disorder common in the sub-Saharan region of Africa. Although sickle cell anemia is generally fatal, having one allele for the disorder is also known to make a person resistant to malaria. Research shows that in the areas where malaria is most common, the sickle cell trait is seen in more than 40% of the total population.
A bioaccumulation
B geographic isolation
C interbreeding
D natural selection