Four children guess the color of the hat.

Because C saw that B was white, if he was white, D at the back would guess his hat, but D didn't say he was black, so D couldn't guess.

Don't make a fool of yourself just because everything is a brain trick. If you say it's a wall, it's a wall. Can you still see through it?

This is obviously a logical question. You still scold others, and BC doesn't look at his answer. It seems that you are BC yourself.

I haven't been so cynical for a long time. I came out to be wronged and was laughed at by a smart-ass to pee.