I'm completely comfortable chatting to other guys. If i'm on some social event, and you show me some random guy, I can start a convo with him no problem. But with girls it doesn't work for me at all, I feel like they are not enthusiastic, I stutter etc.

I see two explanations of this phenomena:

a) I'm more nervous around them and it's all in my head.

b) It's actually easier to start conversations with people of the same sex, because it's obvious that you just want a friendly chat, nothing more.

Which one do you think is true?