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.

Example Input: Fact: Earthworm burrows help aerate soil, which is essential for growing plants. 
Question: Earthworm burrows help aerate soil, which is essential for what?
Example Output: growing plants.

Example Input: Fact: male dogs use natural aphrodisiacs in urine to mark their territory. 
Question: what do male dogs use in their urine to mark their territory?
Example Output: natural aphrodisiacs.

Example Input: Fact: When light goes through the pupil, the iris makes it larger or smaller. 
Question: What makes the pupil change sizes?
Example Output:
The iris.