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: The evaporation of sweat occurs when a body is hot. 
Question: The evaporation of sweat occurs when what thing is hot?
body.

Fact: Heat is necessary for the survival of animals. 
Question: What is necessary for the survival of animals?

heat.