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: boulders are formed by snow, ice, and rock melting sometimes. 
Question: what melts sometimes to form boulders?

Output: snow, ice, and rock.


Input: Consider Input: Fact: Telephones are used for communication by transmitting audible waves. 
Question: Telephones are used for communication by transmitting what?

Output: audible waves.


Input: Consider Input: Fact: energy is used for heating a building by gas. 
Question: what energy is used for heating a building?


Output: gas.