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.

[EX Q]: Fact: lightning ignites fires. 
Question: what can lightning ignite?
[EX A]: fires.

[EX Q]: Fact: mitosis is how organisms grow and repair themselves. 
Question: What is how organisms grow and repair themselves?
[EX A]: mitosis.

[EX Q]: Fact: the type of material through which a longitudinal wave passes changes the speed at which a longitudinal wave travels. 
Question: The type of materila through which what passes changes the speed it travels?
[EX A]:
longitudinal wave.