Haha! I think reality would beg to disagree with that! The only case where you could possibly say "Αυτή είναι φράουλα", dropping the article or it wouldn't work, is this: at a costume party, someone is dressed as a pirate "Αυτός είναι πειρατής", someone else as a wolf "Αυτός είναι λύκος" and then... she is a strawberry! :D
For learners who might use the feminine pronoun in English:
This sentence might make some sense in some languages, with the feminine pronoun she, in colloquial speech (or even formal speech, I'm not aware of every language rule of every language out there, considering that this course might be taken by people who are not native English speakers. :))
However, in English, it sounds very odd, if not incorrect. Technically speaking, she refers to people and/or animals (usually pets, but some people argue that all animals deserve a pronoun. I don't disagree.) . Anything else is referred to as it, and that's a rule we can do nothing about. It might be feminine in Greek, but it's neuter in English. Not all translations are word-for-word.
And to be absolutely sure that your answer will be marked as correct, I suggest that you use the suggested translation, and not search for unusual or one-in-a-million contexts (where this sentence, for example, might be referring to a girl dressed up as a strawberry at a costume party. :P)