Red-Green Color Blind Individuals Do Not Have a Severe Difficulty

Multiple Choice

Red-green color blind individuals do not have a severe difficulty with traffic lights because

A) the red light is always on top and the green light is brighter than the red.
B) the "red" traffic signals have blue light mixed in with the red.
C) the "green" light is really yellow-green.
D) all of these strategies are utilized.