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: melting means changing from a solid into a liquid by increasing temperature. 
Question: what is increased to cause something to change from a solid into a liquid?
Example Output: temperature.

Example Input: Fact: A bill is used for catching prey by some birds. 
Question: What is used by some birds to catch their prey?
Example Output: a bill.

Example Input: Fact: Plants are the major producers in the desert. 
Question: What are major producers in the desert?
Example Output:
plants.