Write a correct answer to the given question based on its associated fact. Make sure that your answer is contained in the associated fact. Don't be creative and introduce any new word that is not mentioned in the associated fact! Remember that the associated fact has been rearranged to form the question. So, the correct answer words must lie within the associated fact. The correct answer can be a word, phrase, or even a sentence.

Q: Fact: Some viruses can cause abnormal cell growth. 
Question: What be caused by some viruses?

A: Abnormal cell growth.
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Q: Fact: mammals can generate heat by muscle action. 
Question: What can mammals generate heat with?

A: Muscle action.
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Q: Fact: Burning fossil fuels increases global warming. 
Question: What kind of fuel use adds the most to global warming?

A:
fossil.
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