Given a fact, create a question that can be answered using the fact. Construct the question such that it is unambiguous, has a unique answer and the answer can be given using the fact.

Q: Fact: many vehicles emit pollution into the air

A: Pollution is?
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Q: Fact: smell is used for finding food by some animals

A: Some animals are aided in finding food sources by?
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Q: Fact: mountains are formed by volcanoes

A:
Which substance is likely present for the birth of a mountain?
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