What Does It Mean That Inhibition of Calcium Channels by Norepinephrine

Multiple Choice

What does it mean that inhibition of calcium channels by norepinephrine is "voltage-dependent"?

A) The inhibition of calcium channels by norepinephrine only occurs if the resting membrane potential is depolarized.
B) Norepinephrine is inhibiting a voltage-gated ion channel.
C) Norepinephrine is activating a voltage-gated ion channel.
D) The inhibition of calcium channels by norepinephrine is enhanced by depolarization.
E) The inhibition of calcium channels by norepinephrine is reduced by depolarization.