Decomposition adds silt to soil. Decomposition adds water to soil. Decomposition adds oxygen to soil. Decomposition adds nutrients to soil.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which of the following statements best explains how the decomposition of plant and animal matter helps to form rich soils?
Possibilities:
- Decomposition adds silt to soil.
- Decomposition adds water to soil.
- Decomposition adds oxygen to soil.
- Decomposition adds nutrients to soil.

Decomposition adds nutrients to soil.