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