In the sequence A, B, C, ?, E, F, what character should replace the question mark?

A. D

In a series of numbers: 2, 4, 8, 16, ?, 64. What is the missing number?

B. 32

In a sequence of letters: A, C, E, G, ?, K. What is the missing letter?

C. H

In the series X, Y, Z, A, ?, C, D, which letter should fill the gap?

A. B

In a pattern of symbols: ?, ?, ?, ?, ?, ?. What is the missing symbol?

A. ?