The correct answer is (a) Methane.
Marsh gas is a flammable gas that is produced by the decomposition of organic matter in wetlands. It is mostly methane, but it can also contain other gases such as carbon dioxide, nitrogen, and hydrogen sulfide.
Ammonia is a colorless gas with a strong odor. It is produced by the breakdown of proteins and other nitrogen-containing compounds. Ammonia is used in many industrial processes, such as the production of fertilizers and explosives.
Nitrogen oxide is a colorless gas that is produced by the combustion of fossil fuels. It is also produced by natural processes, such as lightning. Nitrogen oxide is a major contributor to air pollution.
Carbon monoxide is a colorless, odorless gas that is produced by the incomplete combustion of carbon-containing fuels. It is a major cause of accidental death.
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