In the series: 1, 4, 9, ?, 25, what number should replace the question mark?

A. 16

In the pattern M, N, O, ?, Q, R, what character is missing?

A. P

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

B. 16

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

A. 12

In the sequence P, Q, R, ?, T, U, what character is missing?

A. S