In this task, you're given an open-domain question. Your task is to provide an answer to the given question. There is only one unique answer for each question. Your answer should be short, and refer to an entity, date, number, etc. Do not put your answer in the context of a sentence.
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Question: When does crossing over occur in prophase 1?

Answer: pachytene stage


Question: Who were the first singing brothers inducted into the rock 'n' roll hall of fame?

Answer: The Everly Brothers


Question: Who wrote i heard it on the grapevine?

Answer:
Norman Whitfield