Help the amateur detective interrogate the suspects by choosing the grammatically correct question.

The detective pointed dramatically at the empty cake stand. "Alright, confess! Who ___ my double-chocolate masterpiece?"

The correct answer is ate.

When the question word (like "Who" or "What") is the subject of the sentence, we do not use the auxiliary verbs do, does, or did. We simply use the normal affirmative word order: Who + verb.

"Who did eat" is incorrect because we only use did in object questions or for special emphasis, and "did ate" is grammatically incorrect because did must be followed by a base verb.