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: fields make compasses point north. 
Question: What makes compasses point north?
[A]: fields.


[Q]: Fact: molds have special structures for penetrating a host. 
Question: What has special structures for penetrating a host?
[A]: molds.


[Q]: Fact: precipitation forms caverns. 
Question: What are formed by precipitation?
[A]:
caverns.