Answer:
The correct option is C.
Step-by-step explanation:
According to Darwin's Law of Natural Selection, a gene that benefits the organism and helps it produce healty offspring so that it can survive is supported by natural selection and will receive a positive feedback over.
The fact that the heterozygosity for sickle cell anemia helps with the survivability of malaria, which is a deadly disease, suggests that the heterozygosity is favored by the law of natural selection.
I hope this answer helps.