Complete the series: 12, 24, 48, 96, ?

B. 192

What letter should come next in the series: a, c, e, g, ?

B. H

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

A. U

Find the missing letter in the series: m, n, p, q, ?

A. R

Identify the missing term in the series: 1, 4, 9, 16, ?, 36

B. 25