Consider the following: 1. Rice fields 2. Coal mining 3. Domestic animals 4. Wetlands Which of the above are sources of methane, a major greenhouse gas?

All four options are major sources of methane emissions. 1. Rice fields produce methane through anaerobic decomposition of organic matter in flooded soils, where bacteria thrive in oxygen-poor conditions. 2. Coal mining releases methane that was previously trapped within coal seams and surrounding rock layers during the geological formation of coal. 3. Domestic animals, particularly ruminants like cattle and sheep, produce methane during their normal digestive process known as enteric fermentation. 4. Wetlands are the largest natural source of methane globally, as waterlogged soils create an anaerobic environment where microbes break down organic material. Since all four are recognized sources of methane, the correct answer is D.