Complete the series: b, d, f, h, ?

A. J

What number should replace the question mark in the series: 2, 6, 12, 20, ?

B. 42

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

B. 25

What is the next letter in the series: A, C, E, G, ?

A. I

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

B. S