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.

[EX Q]: Fact: The thyroid gland makes a chemical substance that increase the rate of metabolism in the body. 
Question: What gland makes a chemical in the body to increase the rate of metabolism?
[EX A]: Thyroid.

[EX Q]: Fact: Thyroxine increase the rate of metabolism in cells throughout the body. 
Question: What increases the rate of metabolism in cells throughout the body?
[EX A]: Thyroxine.

[EX Q]: Fact: progesterone is  used in reproduction. 
Question: _is used in reproduction.?
[EX A]:
progesterone.