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

A. J

What letter should come next in the series: b, d, f, h, ?

C. I

What number should come next in the series: 3, 6, 11, 18, ?

A. 25

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

A. J

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

A. R