A parallel-plate capacitor having circular plates of radius R and separation d is charged to a potential difference by a battery. It is then removed from the battery. If the plates are moved farther apart:
A) The amount of charge on each of them will increase.
B) The amount of charge on each of them will decrease.
C) The energy stored in the capacitor remains the same.
D) The energy stored in the capacitor decreases.
E) The amount of charge on each of them will stay the same.