Answer:
Composting protects our ground water supply because:
B. It reduces the need for artificial fertilizers.
Step-by-step explanation:
As explained in the instructions, composting converts organic materials into humus. Humus, a soil-like material, can be used as a natural fertilizer to regenerate poor soils, providing the necessary organic matter for plants to grow. Therefore, composting helps protect our ground water supply because, by using the humus it produces, we reduce the use of artificial fertilizers, which would contaminate the water. Thus, the best option is letter B. It reduces the need for artificial fertilizers.