Like 7 Percent of the Male Population, Lionel Is Red-Green

Like 7 percent of the male population, Lionel is red-green colour blind. Red-green colour blindness is caused by

A) an abnormal number of ganglion cells.
B) a deficiency in one of the three types of cones.
C) hypersensitive sensory adaptation mechanisms.
D) problems with the feature detection system.
E) an imbalance in ganglion cells.