The correct answer is option 4, which states that all three options 1 (domestic animals), 2 (coal mining), and 3 (wetlands) are sources of methane, a greenhouse gas.

1. Domestic animals: Domestic animals, such as cows and sheep, produce methane as a byproduct of their digestive processes. This methane is released through their burps and flatulence.

2. Coal mining: Coal mining is a significant source of methane emissions. Methane can be released during the extraction and transportation of coal. Methane trapped in coal seams can be released into the atmosphere when the coal is mined.

3. Wetlands: Wetlands are natural sources of methane. Methane is produced in wetland soils through the process of decomposition of organic matter under anaerobic (oxygen-deprived) conditions.

Methane is a potent greenhouse gas that contributes to global warming. It has a much higher warming potential than carbon dioxide over a shorter time scale. Therefore, it is crucial to reduce methane emissions from these and other sources to mitigate the impacts of climate change.

Alert - The correct answer should include option 2 (coal mining) as a source of methane, so the correct answer should be option 1, "1 and 2