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

A. E

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

A. P

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

A. E

In the sequence 3, 6, 9, ?, 15, 18, what number should replace the question mark?

A. 12

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

A. D