Sickle cell anemia is a homozygous recessive disorder. This means, in order to have sickle cell anemia, you must have two copies of the recessive allele (aa). Sickle cell anemia can be a lethal disease if proper treatment is not available.

Malaria is a disease that kills hundreds of thousands of people every year. More people die from malaria than sickle cell anemia worldwide. In malaria infested countries, those people who are carriers of the sickle cell allele (Aa) are provided a resistance to malaria, and therefore, are more likely to survive.


Based on the information given, choose the best hypothesis. 
A) Over time, the frequency of the dominant (A) allele would increase in malaria infested populations.

 B) In areas that do not have malaria, there would be an increase in the frequency of the sickle cell (a) allele.

 C) Due to natural selection, the frequency of the heterozygous (Aa) genotype would increase over time in malaria infested populations. 

D) Due to natural selection against the recessive (a) allele in malaria infested areas, there would be a decrease in the number of people who have sickle cell anemia.