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: The mass of the Earth helps cause flowing rivers. 
Question: Which aspect of the Earth is needed to have flowing rivers?
Example Output: Mass.

Example Input: Fact: Insects have more social behaviors because all family members are close relatives. 
Question: Insects have more social behaviors because all what?
Example Output: family members are relatives.

Example Input: Fact: muscle contraction occurs when a diagonally oriented part of muscle gets shorter. 
Question: muscle contraction occurs when a diagonally oriented part of muscle gets what?
Example Output:
shorter.