Identify the missing number in the series: 12, 24, 48, ?, 192.

B. 96

What letter should replace the question mark? x, u, r, o, ?

C. N

Complete the series: z, x, v, t, ?

A. R

What letter comes next in the series: z, x, v, t, ?

C. Q

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

A. J