Find the missing letters in the series: b, d, f, h, ?

A. J

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

C. Q

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

C. Q

Find the missing letter in the series: b, d, f, h, ?

A. J

Identify the missing letter in the series: a, e, i, o, ?

A. U