Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Q: Ocean ridges formed by marine invertebrates living in warm shallow waters within the photic zone of the ocean are called coral reefs.

A: Ocean ridges formed by marine invertebrates living in warm shallow waters within the photic zone of the ocean are called what?
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Q: The male reproductive system consists of structures that produce sperm and secrete testosterone.

A: What does the male reproductive system consist of?
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Q: Acids are associated with a low number on the ph scale.

A:
Acids are associated with a low number on which scale?
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