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.

[EX Q]: Question: What is formed when a subducting plate flows under another tectonic plate? Answer: volcanic arc
[EX A]: A volcanic arc is formed when a subducting plate flows under another tectonic plate.

[EX Q]: Question: What is the diploid number for fruit flies? Answer: 8
[EX A]: 8 is the diploid number for fruit flies.

[EX Q]: Question: What are ocean waves mainly caused by? Answer: wind
[EX A]:
Ocean waves are mainly caused by wind.