How does sickle-cell disease exemplify the concept of pleiotropy ?

Sickle cell anemia is a pleiotropic disease because the expression of a single mutated HBB gene produces numerous consequences throughout the body. The mutated hemoglobin forms polymers and clumps together causing the deoxygenated sickle red blood cells to assume the disfigured sickle shape.

C) primary producers because you have to have enough food to even start a food web