Which gas is predominantly emitted during the combustion of fossil fuels containing sulfur?

The predominant gas emitted during the combustion of fossil fuels containing sulfur is sulfur dioxide. When fossil fuels such as coal, oil, or natural gas are burned, they undergo a chemical reaction that produces energy, carbon dioxide, water vapor, and various other compounds.

In the case of fuels that contain sulfur, the sulfur component reacts with oxygen during combustion to form sulfur dioxide. This is a significant concern because sulfur dioxide is an air pollutant that can lead to acid rain and has detrimental effects on the environment and human health.

While carbon dioxide and water vapor are common byproducts of combustion, they do not specifically relate to the sulfur content in fuels. Methane is not a product of the combustion of fossil fuels containing sulfur; rather, it is a fossil fuel itself. Therefore, sulfur dioxide is the correct answer, as it directly results from the burning of sulfur-containing fossil fuels.