What letter comes next in the series: m, o, q, s, ?

A. T

Complete the series: a, e, i, o, ?

A. U

What is the next number in the series: 3, 7, 15, 31, ?

A. 63

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

A. R

What letter comes next in the series: z, x, v, t, ?

C. Q