In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.

Question: What in the axils of leaves and stems give rise to branches? Answer: axillary buds
Axillary buds in the axils of leaves and stems give rise to branches.

Question: What occurs when a substance reacts quickly with oxygen? Answer: combustion reaction
Combustion reaction occurs when a substance reacts quickly with oxygen.

Question: In a tropical rainforest, where are ferns common? Answer: understory

In a tropical rainforest, understory are ferns common.