In this task, you need to write a topic word from the given fact. The topic word must have at least one word overlap with the given fact. The topic word often involves adding a new word from a related concept. In your topic word, use at least one word from the given fact. Topic words with two or more words work best.

Q: Fact: Muscle contraction occurs when muscle fibers get shorter.

A: Muscle contraction.
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Q: Fact: matter vibrating can cause sound.

A: cause sound.
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Q: Fact: a polar bear requires a cold environment.

A:
cold arctic.
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