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: hormones control heart rate. 
Question: What do hormones control?
Heart rate.

Fact: Natural magnetism is used for pointing north in a surveying tool. 
Question: Who would use a tool that uses a magnet that points north?
surveyor.

Fact: a flashlight coverts chemical energy into a form of electromagnetic energy. 
Question: What can flashlights convert chemical energy into?

electromagnetic energy.