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.

Input: Consider Input: Fact: animals use sound to find a mate. 
Question: What do animals use to find a mate?

Output: sound.


Input: Consider Input: Fact: Playing is just one of many ways that humans and other animals learn how to behave. 
Question: What uses playing as just one of many ways to learn how to behave?

Output: Humans.


Input: Consider Input: Fact: Organic matter being buried under mud changes peat into coal. 
Question: what being buried under mud changes peat into coal?


Output: organic matter.