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

B. 12

In the pattern P, Q, R, ?, T, U, which character is missing?

A. S

In the sequence 2, 4, 8, ?, 32, what is the missing number?

B. 16

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

A. P