Which of the following best describes biosolids?

Biosolids refer to treated sewage sludge that is rich in nutrients and can be safely used as fertilizer. After the wastewater treatment process, sludge is generated, which contains organic matter and nutrients that can be beneficial for soil health and agricultural productivity. The treatment process ensures that pathogens and contaminants are reduced to safe levels, making the biosolids a viable option for enhancing soil fertility and structure when applied to land.

This option highlights the essential process of treatment that transforms potentially harmful sewage sludge into a resource, emphasizing its role in nutrient management practices. In contrast, the other choices do not accurately capture the definition of biosolids. Unprocessed organic materials from composting are distinctly different from treated sewage sludge, natural minerals found in soil refer to inorganic constituents that do not relate to the treatment of waste, and compost made from vegetable scraps does not encompass the more comprehensive treatment process that biosolids undergo.