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: The direction the earth is tilted while it orbits the sun is what causes climate to change. 
Question: What determines the climate to change?
The way the earth is tilted.

Fact: many chemical messengers that control body functions are proteins. 
Question: What are many chemical messengers that control body functions?
proteins.

Fact: if copper is exposed to heat, it may become hot. 
Question: what may become hot when exposed to heat?

copper.