LMNO
MNO
MNOP
NOPQ
Answer is Wrong!
Answer is Right!
The correct answer is $\boxed{\text{LMNO}}$.
The sequence is a simple alternating repetition of the letters A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y.
The first two terms are A and C. The third term is GHI, which is formed by taking the first two letters of the previous two terms, A and C, and then the first two letters of the third term, G and H.
The fourth term is LMNO, which is formed by taking the first two letters of the previous two terms, GHI and A, and then the first two letters of the fourth term, L and M.
Therefore, the missing term is LMNO.