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.

[Q]: Fact: All birds have backbones. 
Question: Which animal has a backbone?
[A]: bird.


[Q]: Fact: jogging requires energy. 
Question: What requires energy?
[A]: jogging.


[Q]: Fact: being buried under soil and mud change vegetation into fossil fuels. 
Question: What does being buried under soil and mud change vegetation into?
[A]:
Fossil fuels.