Domestic waste dumping is the main cause of Yamuna River pollution in Delhi. Unprecedented urbanization results in untreated sewage, household refuse, and industrial discharge entering the river directly. This has resulted in extreme water contamination, with dangerously high concentrations of poisons and refuse. Although pesticides and fertilizers contribute to pollution in agricultural regions, the primary driver of Yamuna pollution in Delhi remains the discharge of domestic waste.Therefore, the appropriate choice is (B) Domestic waste dumping.