The correct answer is option 2: Methane.

Rice fields are known to have a significant impact on global methane emissions. Methane is a greenhouse gas that has a much higher global warming potential compared to carbon dioxide. It is released during the decomposition of organic matter in anaerobic (oxygen-deprived) conditions, such as waterlogged rice fields.

Option 1: Carbon dioxide (CO2) is also emitted from rice fields, but in lesser quantities compared to methane. Carbon dioxide is a greenhouse gas but has a lower global warming potential than methane.

Option 3: Carbon monoxide (CO) is not primarily released from rice fields. It is mainly produced from incomplete combustion of fossil fuels.

Option 4: Sulphur dioxide (SO2) is not released from rice fields. It is primarily emitted from burning fossil fuels containing sulfur, like coal and oil.

In summary, while other gases like carbon dioxide, carbon monoxide, and sulphur dioxide may be emitted from various sources including human activities, methane is the gas released in the most prominent quantities from rice fields.