In a sequence of letters: Z, Y, X, W, ?, U. What is the missing letter?

A. V

What character should replace the question mark in the sequence 3, 6, 9, ?, 15?

B. 12

In the pattern 1, 3, 5, ?, 9, 11, what is the missing number?

B. 7

What character should replace the question mark in the sequence: A, B, C, ?, E?

A. D

What character should replace the question mark in the sequence: A, B, C, ?, E?

A. D