The Opponent-Process Theory of Color Vision Accounts for the Observation

The opponent-process theory of color vision accounts for the observation that

A) after staring at something of one bright color for a while, we can look away and see a different color.
B) the most common kind of color vision deficiency is much more common in men than it is in women.
C) we have better color vision in the fovea than we do in the periphery of the eyes.
D) it is easier to see small red spots from a distance than it is to see equally small blue spots from the same distance.