Given a statement, generate a question such that the answer is contained in that statement.
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Question: optical instruments help explain the natural world

Answer: What help explain the natural world?

Question: Running requires a lot of calories.

Answer: What does running require?

Question: a thinning and weakening of bone is an affliction in which osteoclasts are more active than osteoblasts

Answer:
What are more active than osteoblasts?