Question

A farmer planted legumes and cabbage in the same field that is devoid of fertilizers. The yield from this field is better than the cabbage planted in another field without legumes. Why?

a.) nitrogen-fixing bacteria present in the roots of legumes aid in the enrichment of nitrogen in the soil.
b.) nitrogen-fixing bacteria present in the roots of legumes inhibit the growth of weeds or unwanted plants.
c.) nitrogen-fixing bacteria present in the roots of legumes prevent bacterial growth that cause root diseases.?????