Find the missing letter in the series: B, D, F, H, ?

A. J

What is the next letter in the series: A, C, E, G, ?

A. I

What is the next letter in the series: A, C, E, G, ?

B. H

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

A. J

Identify the incorrect letter in the series: A, B, D, E, G, H, J

B. D