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: Mutations can be detected by analysis on gene abnormalities. 
Question: Which process of gene abnormalities can mutations be detected?
Example Output: analysis.

Example Input: Fact: Water must not be polluted to be safe. 
Question: What can happen to water to make it unsafe?
Example Output: Pollution.

Example Input: Fact: Incandescent lights heating a metal filament are used for seeing in the dark. 
Question: What is used for used for seeing in the dark?
Example Output:
Heating a metal filament.