There are three bags - one with apples, one with oranges and one with both apples and oranges... Each bag has a label showing what it contains. Unfortunately all labels have been wrongly placed on the bag. If you are allowed to select only 1 bag and look inside, which one will you choose to finally place all labels correctly ?

Since ALL labels are wrong, the bag labeled 'Apples and Oranges' CANNOT contain both fruits. Pick that bag first - if you see an apple, it must contain ONLY apples. Then the bag labeled 'Oranges' (wrong label) cannot contain oranges, and since the mixed bag contains apples, it must contain both. The bag labeled 'Apples' then contains oranges. Similar logic if you first see an orange.