I am going to guess A- female B-male, and C-? I am used to tree frogs which you always assume the fat ones are females and the smaller skinny ones are males. But then I thought I had 2 female azureus which turned out to be a pair. (Both pairs laid for the first time this week WOOHOO!) I think it helpsa to look at a side profile and look for differences in the curvature of the back as well.