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: Chemical weathering causes FE in rock to oxidize. 
Question: Chemical weathering causes what in rock to oxidize?
[A]: Fe.


[Q]: Fact: a polar bear requires extremely low humidity. 
Question: what does a polar bear require?
[A]: extremely low humidity.


[Q]: Fact: Plants require potash to grow. 
Question: What do plants require to grow?
[A]:
potash.