Leukopenia is a condition characterized by a decrease in white blood cells. what effect does leukopenia have on the body's ability to fight infection?

Leukopenia means  a low count of white blood  cells in the body. When there is a low white blood cell count in the body, and in particular a low level of neutrophils (a kind of white blood cell that fights infection), there is quite a significant risk of developing an infection, and once an infection is developed and the white blood cell count is low, the body will not be able to protect itself and fight off the infection. In severe cases , infection may lead to death.

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).   so the answer is a.