There are 3 boxes. One has apples, one has oranges and one has both. All the labels are wrong. You may pick one fruit from one box. From how many boxes must you pick a fruit to label all the boxes correctly?

Answer: A. 1

Pick a fruit from the box labelled "Apples + Oranges". Since its label is wrong, it holds only one kind of fruit, and the fruit you pick tells you which. The other two labels are also wrong, so the remaining two boxes can then be labelled correctly. So you need to check only 1 box.

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