Which be at illustrates a result of natural selection

Sickle cell anemia

Explanation:

sickle cell anemia is a disease in which red blood cell haemoglobin A is replaced by an abnormal form called hemoglobin S. The result is deformation of red blood cells at low oxygen concentrations leading to anemia. Sickle cell trait is fairly common in some parts of Africa and Asia but rare in other continents. This high incidence of the trait in some areas suggests that it may have some survival value. The trait occurs with high prevalence in areas where malaria is endemic. People with the trait have a higher resistance to malaria than normal individuals.