Answer: A. They are used as fertilizer on hay fields.
Step-by-step explanation:
Solid wastes are the unwanted wastes that are generated by different sources such as domestic wastes, agricultural, and industrial wastes. These wastes are treated with several waste management processes such as use of landfill, incineration, dumping and humification. The biodegradable wastes can be transformed into slury which can be used as a natural fertilizers in the hay fields.