Complete the series: m, o, q, s, ?

A. T

Identify the missing letter in the series: a, e, i, o, ?

A. U

What letter comes next in the series: M, O, Q, S, ?

B. T

Identify the missing letter in the series: Z, X, V, T, ?

A. S

Which letter should replace the question mark in the series: B, D, F, H, ?

D. I