Which of the following hypothetical observations (if it were true) would tend to refute the trichromatic (Young-Helmholtz) theory of color vision?
A. Color-blind people who cannot see red objects can nevertheless see green and blue objects without any trouble
B. No combination of red, green, and blue lights can match a brown light.
C. People who wear red-tinted glasses cannot identify any colors other than red.
D. Someone who stares at a bright red object for a minute and then looks away sees a gray afterimage.