Task: Paraphrasing
Input (English): Question: What is a primary role of decomposers in an ecosystem? 
Answer: They cycle matter by returning carbon and other matter to the ecosystem. 
Sentence: A primary role of decomposers in an ecosystem is that they cycle matter by returning carbon and other matter to the ecosystem.
Output (English): A decomposer's primary role is to return carbon and other matter to the ecosystem through a cycle.