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.

[Q]: Fact: Smog is an airborne pollutant. 
Question: What is an airborne pollutant?
[A]: Smog.


[Q]: Fact: nails prevent water loss. 
Question: what do nails prevent?
[A]: water loss.


[Q]: Fact: carbon monoxide is produced when heating homes. 
Question: what produces carbon monoxide?
[A]:
heating homes.