Which of the following statements correctly describes energy levels? Answer Review

A. In its outermost energy level, oxygen has 4 valence electrons.
B. The second energy level holds a maximum of eight electrons.
C. Electrons can never move to a higher or lower energy level.
D. The greater the energy of the level, the farther away it is from the nucleus.

I think its B or C. In my opinion they're both correct, I may be wrong. Can someone please clarify?