GWD 5-14

Q14: If a code word is defined to be a sequence of different letters chosen from the 10 letters A, B, C, D, E, F, G, H, I, and J, what is the ratio of the number of 5-letter code words to the number of 4-letter code words?

A.5 to 4  B.3 to 2   C.2 to 1   D.5 to 1   E.6 to 1

MINE D

ANS E

怎么也不明白啊