Which one of following conditions though harmful in itself, is also a potential survivor from a mosquito borne infectious disease?

Sickle cell anemia is caused by a variant form of hemoglobin in red blood cells. The amino acid valine replaces glutamine in the 6th position in hemoglobin chain. The homozygous individuals die at an early stage. In heterozygotes also, the red blood cells with a variant form of hemoglobin become sickle shaped. Due to this, the RBCs are unable to bind oxygen efficiently. As sickle shaped RBCs are destroyed the malarial parasite is killed. This allows the individual heterozygous for this variant to be able to deal with malaria infections much better than a normal person. Hence a person with sickle cell anemia is also a potential survivor from a mosquito borne infectious disease such as malaria. Thus the correct answer is option B.