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: Mutations that lead to cancer usually occur in genes aiding in mitosis. 
Question: Mutations that lead to cancer usually effect genes that aid in what?

Answer: mitosis.


Question: Fact: erosion forms canyons. 
Question: What are formed by erosion?

Answer: canyons.


Question: Fact: Sleep is good for human health. 
Question: What may improve health?

Answer:
sleep.