Translation:Did you already answer the question?
I have just looked it up on the Wiktionary, and I think the answer (!) lies in the verb’s object: when used transitively, its object is the answer to the question, not whom one is speaking to.
(intransitive) to answer a question
Muttsu no shitsumon ni kotaeru.
I will answer six questions.
(transitive) to say in reply to a question
Namae o kotaeta.
She gave her name.
Thats what i wrote and I'm fairly sure it should be accepted. The difference is between past simple tense and past perfect tense. If Japanese does not have a distinction between these two tenses, then I think our answer should be accepted. It is a correct English sentence.