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: bears hibernate to conserve energy. 
Question: Why do bears hibernate?

Output: conserve energy.


Input: Consider Input: Fact: Stimuli can cause the brain to experience pain. 
Question: What can cause the brain to experience pain?

Output: stimuli.


Input: Consider Input: Fact: Urea is a waste product of the body that is excreted by the urinary system. 
Question: What is a waste product of the body that is excreted by the urinary system?


Output: urea.