Complete the series: b, d, f, h, ?

D. I

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

C. I

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

A. S

Complete the series: a, e, i, o, ?

A. U

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

C. I