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: Earthworm burrows help aerate soil, which is essential for growing plants. 
Question: Earthworm burrows help aerate soil, which is essential for what?
[A]: growing plants.


[Q]: Fact: oxygen is essential for cellular respiration for fungi. 
Question: what requires oxygen for cellular respiration?
[A]: fungi.


[Q]: Fact: Day and night on a planet, in cycles, is caused by the momentum of the planet's orbit. 
Question: A planet experiences day and night cycles, due to the planet's what?
[A]:
orbit momentum.