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.

Fact: most mammals have insulation that also protects the body. 
Question: What has insulation that also protects the body?
most mammals.

Fact: Producers use unsaturated fatty acids to store energy. 
Question: What kind of organism uses unsaturated fatty acids to store energy?
producers.

Fact: Optical tools are used for observing things that are smaller than they appear. 
Question: Optical tools are used for observing things that are smaller than what?

they appear.