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.

Fact: memory cells help keep people from getting sick. 
Question: What helps keep people from getting sick?
Memory cells.

Fact: Force being exerted on a soccer ball compresses it. 
Question: Force being exerted on a soccer ball does what?
compresses it.

Fact: earthworms have the amazing capacity to regrow segments that break off. 
Question: _have the amazing capacity to regrow segments that break off.?

earthworms.