What character should fill the blank in the sequence X, Y, ?, Z?

B. B

In the series X, Y, Z, ?, B, C, what character should replace the question mark?

A. A

In the pattern 2, 4, 8, ?, 32, what number should replace the question mark?

B. 16

In the sequence 3, 6, 9, ?, 15, 18, what number should replace the question mark?

B. 12

Find the missing letter in the series M, N, O, ?, Q, R.

A. P