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.

[Q]: Fact: Lung cancer is most often caused by exposure to cigarettes. 
Question: What is lung cancer most often caused by exposure to?
[A]: cigarettes.


[Q]: Fact: An object's shape can be changed by removing material. 
Question: What is one way an object's shape can be changed?
[A]: removing material.


[Q]: Fact: bearings can heat up because of friction. 
Question: what can cause bearings to heat up?
[A]:
friction.