Identify the missing letter in the series: Z, Y, X, W, ?

A. V

Complete the series: B, D, F, H, ?

C. I

Complete the series: B, D, F, H, ?

A. J

Find the incorrect letter in the series: A, D, G, J, M, P, S

D. J

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

A. U