instruction:
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: Fanning a fire helps it to continue burning. 
Question: What can help a fire to continue burning?
answer:
Fanning it.


question:
Fact: animals use sound to find a mate. 
Question: What do animals use to find a mate?
answer:
sound.


question:
Fact: fertilization requires water. 
Question: what requires water?
answer:

fertilization.