instruction:
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: Some mollusks are not easily seen with the naked eye. 
Question: What are not easily seen with the naked eye?
answer:
mollusks.


question:
Fact: animals use sound to find a mate. 
Question: What do animals use to find a mate?
answer:
sound.


question:
Fact: Some wasps, and certain flies and nematodes kill their host, but most do not. 
Question: Some wasps, and certain flies and nematodes kill their what, but most do not?
answer:

host.