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.
--------
Question: Fact: Most animals without backbones have a nervous system. 
Question: Which type of system do most animals without backbones have?

Answer: Nervous system.


Question: Fact: lightning ignites fires. 
Question: what can lightning ignite?

Answer: fires.


Question: Fact: eggs are used to reproduce. 
Question: what are used to reproduce?

Answer:
eggs.