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.
--------
Question: Fact: AIDS infects and destroys helper T cells. 
Question: what infects and destroys helper T cells?

Answer: AIDS.


Question: Fact: small capillaries collect fluid. 
Question: What collects fluid?

Answer: small capillaries.


Question: Fact: Mercury expanding and rising in a tube is used to measure temperature. 
Question: What expanding and rising in a tube is used to measure temperature?

Answer:
mercury.