Explanation
The option (D) Synthetic Chemicals is not used in organic farming.
Organic farming practices rely on natural methods and materials to enhance soil fertility, control pests and diseases, and promote sustainable agricultural systems. Synthetic chemicals, including synthetic fertilizers and pesticides, are not permitted in organic farming. Instead, organic farming emphasizes the use of crop rotation, organic manures (such as compost and animal manure), and biofertilizers (microorganisms that enhance soil fertility) to maintain soil health and support plant growth.