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: A thing arranged in clusters mostly contain instructions for a single protein. 
Question: How often does a thing arranged in clusters contain instructions for a single protein?
mostly.

Fact: Ozone depletion increases the risk of getting skin cancer. 
Question: What increases the risk of getting skin cancer?
Ozone depletion.

Fact: birds fly using muscles in the chest. 
Question: What do birds use to fly?

Muscles in the chest.