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: A person's elbow straightens when muscles antagonistic to biceps contract. 
Question: A person's elbow straightens when muscles antagonistic to what contract?

A: biceps.
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Q: Fact: breathing is when fish convert from oxygen in water to oxygen in blood. 
Question: When fish convert oxygen in water to oxygen in blood this is called?

A: breathing.
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Q: Fact: Adult echinoderms lack an anterior and posterior end. 
Question: Which of the following does not have an anterior and posterior end?

A:
Adult echinoderms.
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