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: wiring requires metals. 
Question: What can you use in wiring to produce current?
answer:
metals.


question:
Fact: cell regeneration requires rest. 
Question: what requires rest?
answer:
cell regeneration.


question:
Fact: cycles of freezing and thawing water causes mechanical weathering. 
Question: what do cycles of freezing and thawing water cause?
answer:

mechanical weathering.