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: the threat of being eaten causes a porcupine to extend its quills. 
Question: What threat would cause a porcupine to extend its quills?
being eaten.

Fact: Many consumers feed at more than one nutrient level. 
Question: Many consumers feed at more than one what?
nutrient level.

Fact: the digestive system uses catabolism to produce nutrients for the body. 
Question: what does the digestive system use to produce nutrients for the body?

catabolism.