Among the following crops, which one is the most important anthropogenic source of both methane and nitrous oxide?

Answer: B. RICE is the most important anthropogenic source of both methane and nitrous oxide among the listed crops. RICE PADDY FIELDS are the largest crop-based source of both gases: METHANE (CH4): Flooded rice paddies create anaerobic conditions in soils where methanogenic archaea decompose organic matter, producing methane. Rice cultivation accounts for about 11-12% of global anthropogenic methane emissions and 1.5% of all global GHG emissions. NITROUS OXIDE (N2O): Heavy nitrogen fertiliser use in rice (combined with anaerobic conditions) drives nitrification-denitrification cycles releasing N2O, a powerful greenhouse gas (273x more potent than CO2 over 100 years). Distractors: (A) Cotton consumes water and pesticides but is not a major methane source. (C) Sugarcane releases some N2O but not at the scale of rice methane. (D) Wheat is grown aerobically, generates only minor methane; N2O emissions exist but lower than rice. Source: IPCC AR6 / FAO Climate Change and Food Security reports / NCERT Class 12 Biology Ch 13.