11 week old orp/leghorn crosses. Help me sex them?

[justduckyinVT]

I'm new to chickens so some may find it quite obvious but after looking at several Leghorn pictures of both hen and roo, I've noticed that they both have substantial combs and wattles. It leaves me with questions about my young birds. I'm wondering about one bird in particular. I'll call it A, the second one B, I feel is a rooster for sure, He crows. I hatched them both out of white eggs. The rooster over them was a Buff Orpington, the hen could have been a California White or a Cornish Cross. The above is the bird in question. A

This bird crows.
Thanks for your help.

 

[sourland]

B is for sure a cockerel. A may just be an early developing pullet.