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: force causes the speed of a crystal ball to increase. 
Question: What can force affect the speed of?
a crystal ball.

Fact: skin is cooled by evaporation. 
Question: What cools the skin?
evaporation.

Fact: males and females engage in courtship. 
Question: What engages in courtship?

Males and females.