In this task, you're given an ambiguous question (which can be answered in more than one way). Your task is to write a question that clarifies the given question in such a way that the generated question has one unique answer.
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Question: What is the upper most layer of soil?

Answer: What is the upper most layer of soil called?


Question: What percentage of the us population has a phd?

Answer: For people age 25-30, what percentage of the US population has a phd?


Question: When was the last time the us hosted a world cup?

Answer:
Which world cup was the last time the us hosted a men's world cup?