PrepSwift: Factors of Factorials Q2

In Question 2 which asks for which of the following is a factor of 15!, I answered 5 which is an obvious answer. And I got wrong because 5^2 and 5^3 are also the answer. I could understood why those are also the answers after looking at the explanation but the way the choices look like exponent made me confused. Is it just the problem of how the question and answer choices were designed or is it just my understanding problems?

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