The letter designations for the first four sublevels, with the number of electrons that can be accommodated in each sublevel are A
s: 2, p: 8, d: 8, and f: 18.

B
s: 1, p: 2, d: 3, and f: 4.

C
s: 2, p: 6, d: 10, and f: 14.

D
s: 1, p: 3, d: 10, and f: 14.

E
s: 1, p: 3, d: 5, and f: 7.