by adding carbon by adding nitrogen by removing excess water by removing excess minerals
I gave my students this multiple choice question: Decomposers increase the fertility of the soil and prevent dead organisms from building up in the environment. In which way do decomposers make the soil more fertile?

Only one answer is correct among these 4 choices:
- by adding carbon
- by adding nitrogen
- by removing excess water
- by removing excess minerals

Could you tell me which one is correct?

by adding nitrogen