A, C, E, G, ?

A. I

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

A. U

Complete the series: x, u, r, o, ?

A. L

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

B. S

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

D. I