Which of the following provides an example of epistasis?
a) recessive genotypes for each of two genes (aabb) results in an albino corn snake.
b) the allele b17 produces a dominant phenotype, although b1 through b16 do not.
c) in rabbits and many other mammals, one genotype (cc) prevents any fur color from developing.
d) in drosophila (fruit flies), white eyes can be due to an x-linked gene or to a combination of other genes.
e) in cacti, there are several genes for the type of spines.