Find the missing letter in the series: b, d, f, h, ?

A. J

What is the next number in the series: 12, 24, 48, 96, ?

A. 192

A, C, E, G, ?

A. I

What is the missing term in the series: 2, 6, 12, 20, ?, 42

B. 32

Z, Y, X, W, ?

A. V