What will come in place of the question mark (?) in the following letter series? M, O, Q, S, U, ? MCQ with Answer and Explanation

Explanation:
First letters: O, P, Q, R, S (+1). Second letters: Q, R, S, T, U (+1). The next term is SU.

Explanation:
In this letter series, each letter is shifted one position forward in the English alphabet. S+1=T, C+1=D, D+1=E. Continuing this pattern: U+1=V, G+1=H, so the missing term is VIJ.[reference:0]

Explanation:
First: C, I, O, U, A (+6 each, wrap). Second: F, L, R, X, D (+6 each, wrap). So AD.