M, N, O, P, ?

A. Q

What is the next number in the series: 10, 20, 30, 40, ?

B. 50

Identify the missing term in the series: 3, 7, 15, 31, ?, 127

A. 63

What is the missing number in the series: 10, 20, 40, 80, ?, 320

A. 160

What letter comes next in the series: d, f, h, j, ?

A. K