Botanically, strawberries are not true berries, but bananas, watermelons, and pumpkins are.
Why it is true
A true botanical berry develops from a single flower with one ovary and contains seeds inside, which applies to bananas and watermelons, but not to strawberries, whose seeds are on the outside.
Source: Botany
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.