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: Coal is used to produce the movement of electrons by burning in coal-fire power stations. 
Question: Coal is used to produce the movement of electrons by what in coal-fire power stations?

Answer: burning.


Question: Fact: Plastic slows the transfer of electricity. 
Question: Which material slows the transfer of electricity?

Answer: Plastic.


Question: Fact: A cactus stem is used for storing H20. 
Question: A cactus stem is used for storing what?

Answer:
H20.