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: Smog is an airborne pollutant. 
Question: What is an airborne pollutant?

Output: Smog.


Input: Consider Input: Fact: food can cause illness. 
Question: What is a source of  illness?

Output: food.


Input: Consider Input: Fact: fourty percent of the total mass of organisms at a trophic level is carbon. 
Question: What is fourty percent of the total mass of organisms at a trophic level?


Output: carbon.