The correct answer is: A. CO2
Carbon dioxide (CO2) is the most abundant greenhouse gas in Earth’s atmosphere. It is produced by the burning of fossil fuels, such as coal, oil, and natural gas, as well as by the decomposition of organic matter. CO2 is also released into the atmosphere when forests are cleared.
Nitrous oxide (N2O) is a greenhouse gas that is produced by human activities, such as agriculture, fossil fuel combustion, and industrial processes. N2O is also released into the atmosphere from natural sources, such as volcanoes and soil.
Methane (CH4) is a greenhouse gas that is produced by human activities, such as agriculture, fossil fuel production and transport, and waste management. Methane is also released into the atmosphere from natural sources, such as wetlands and termites.
Ozone (O3) is a greenhouse gas that is produced in the stratosphere by the interaction of ultraviolet radiation with oxygen molecules. Ozone is also released into the atmosphere from human activities, such as the use of chlorofluorocarbons (CFCs).
CO2 is the most potent greenhouse gas because it has a long lifetime in the atmosphere and it absorbs infrared radiation very effectively. N2O is the second most potent greenhouse gas, followed by CH4 and O3.