If you stare at a white circle surrounded by a green background, and then look at a white surface, you perceive a green circle surrounded by a red background. What does this observation imply about the opponent-process theory?

a. We perceive colors based on the pattern of input to the bipolar and ganglion cells of the retina.

b. The mechanisms of color vision vary from one species to another.

c. Opponent-process color perception depends on the visual cortex, not just the cells in the retina.

d. The opponent-process theory is wrong.