What Is the Contrast Principle of Perception

What is the contrast principle of perception?

A) That some stimuli are seen better against light than dark backgrounds.
B) That presenting two items in succession that differ substantially from one another in some way will make the second seem even more different from the first than it is.
C) That presenting two items in succession that are quite similar to one another will make the second seem even more similar to the first than it is.
D) None of the above.