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

A. R

Complete the series: B, D, F, H, ?

D. I

Complete the series: B, D, F, H, ?

A. J

Identify the missing letter in the series: Z, X, V, T, ?

B. S

What letter should come next in the series: a, c, e, g, ?

B. H