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: Birds have backbones. 
Question: What animals have a backbone?
Birds.

Fact: Condensation causes sun blocking and temperature drops. 
Question: What causes sun blocking and temperature drops?
condensation.

Fact: Producing heat causes air pollution. 
Question: What causes air pollution?

producing heat.