instruction:
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.
question:
Fact: a polar bear requires extremely low humidity. 
Question: what does a polar bear require?
answer:
extremely low humidity.


question:
Fact: when an earthquake causes the ground to shake, this shaking can damage buildings. 
Question: How do earthquakes cause damage to buildings?
answer:
The shaking of the ground causes damage to buildings.


question:
Fact: Pasteurization reduces the amount of unicellular organisms in milk. 
Question: Pasteurization reduces the amount of what in milk?
answer:

unicellular organisms.