If the pattern is 1, 2, 4, ?, 16, what number should replace the question mark?

B. 8

In the series X, Y, ?, Z, what character is missing?

A. W

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

C. 12

If the pattern is A1, B2, C3, ?, E5, what should replace the question mark?

A. D4