P.S. But you know what? It could just be the uniform. I'm a tall butch and I use big shirts and flannels to give the effect as if I didn't have breasts, and most of the times people think I'm a guy. But other than that I had realized that the dark hair chick is wearing a rather large uniform with a short skirt, so it could be the uniform giving the effect of small breasts and she might be a B cup (from my guess).
And sorry for all the blabbering ^~^ Went too deep on details..