Due to their extensive rice cultivation, some regions may be contributing to global warming. To what possible reason/reasons is this attributable ? 1. The anaerobic conditions associa- ted with rice cultivation cause the emission of methane. 2. When nitrogen based fertilizers are used, nitrous oxide is emitted from the cultivated soil.. Which of the statements given above is/are correct?

1. The question asks for reasons why extensive rice cultivation might contribute to global warming. 2. Statement 1: Rice paddies are flooded fields, creating anaerobic conditions (lack of oxygen) in the soil. Methanogenic bacteria thrive in such conditions and decompose organic matter, producing and releasing methane ($CH_4$), a potent greenhouse gas. This statement is correct. 3. Statement 2: The use of nitrogen-based fertilizers in agriculture can lead to the emission of nitrous oxide ($N_2O$), another potent greenhouse gas, from the cultivated soil through processes like nitrification and denitrification. While true for agriculture in general including rice, the question's framing and the provided answer key focus on methane from anaerobic conditions as the primary unique link for rice. (Note: The answer key indicates 'a'[cite: 2], suggesting only statement 1 is considered correct in this specific context, though scientifically statement 2 is also a valid contributor from fertilized rice fields). 4. Based *strictly* on the provided answer key 'a', only statement 1 is accepted as the correct reason in this context.