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

D. U

Z, X, V, T, ?

A. R

Find the odd one out in the series: A, C, E, G, H, I, K.

C. H

A, E, I, M, ?

A. O

What comes next in the series: A, E, I, M, ?

A. O