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

Fact: Some parasites survive on the surface of their host. 
Question: Where so parasites go to survive?
on a host.

Fact: mutations change characteristics of living things over time. 
Question: What causes changes in characteristics of living things over time?

mutations.