instruction:
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.
question:
Fact: Birds have backbones. 
Question: What animals have a backbone?
answer:
Birds.


question:
Fact: blood traveling to the heart is deoxygenated. 
Question: Blood traveling to the heart is?
answer:
deoxygenated.


question:
Fact: dirt can be depleted of nutrients. 
Question: What can be depleted of nutrients?
answer:

dirt.