In this puzzle we have $3$ boxes containing only apples, only oranges, and apples and oranges each.
The boxes are closed and labeled: apples, oranges, and apples and oranges, but we know for a fact that these labels are incorrect.
Our task is to put the labels in the right boxes. We can ask for showing us one fruit from one box of our choose, but without showing us the entire content of this box.
What box should we choose? Why?