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: Roots have parts that regenerate after bisection. 
Question: What have parts that regenerate after bisection?
roots.

Fact: The cause of smallpox is usually thought to be nonliving. 
Question: Many believe the cause of smallpox to be what?
Nonliving.

Fact: mammals are vertebrates. 
Question: what are vertebrates?

mammals.