Final answer:
Among the twenty-five crates, there are at least nine containing the same sort of apple.
Step-by-step explanation:
To show that among the twenty-five crates there are at least nine containing the same sort of apple, we can use the Pigeonhole Principle.
Since there are three different sorts of apples and only 8 crates of each sort would be needed to have 24 different crates, if we have 25 crates, at least 9 of them must contain the same sort of apple.