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: An animal requires oxygen for survival. 
Question: What does an animal need for survival?
Oxygen.

Fact: barometric pressure makes clear weather. 
Question: What causes clear weather?
barometric pressure.

Fact: threatening behavior by predators causes a rodent to extend its quills. 
Question: What extends something because of threatening behavior by predators?

A rodent.