Complete the series: x, u, r, o, ?

A. L

Find the missing letter in the series: z, x, v, t, ?

A. R

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

A. J

Identify the missing letter: x, u, r, o, ?

A. L

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

A. J