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 light bulb is used for seeing at night. 
Question: a light bulb is used for seeing?
at night.

Fact: nails prevent water loss. 
Question: what do nails prevent?
water loss.

Fact: Roots grow away from a light source. 
Question: what grow away from a light source?

roots.