Help with question

[Kalee20]

The capacitance of a variable capacitance diode
A. increases with increasing voltage when forward biased.
B. decreases with increasing voltage when forward biased.
C. increases with increasing voltage when reverse biased.
D.* increases with decreasing voltage when reverse biased.

Answer is D. This one had my head spinning, till I looked it up.
Talk about making it more complicated than it need be.
Simple answer increases with less reverse bias.

Strictly speaking, A is also correct! At zero bias you can measure a certain capacitance (as long as you are only applying a few tens of mV test voltage), if you forward bias with 100mV you'll measure more capacitance. When you get to 500mV the thing starts to turn on and capacitance becomes meaningless, though an instrument might read infinity.