The correct answer is C. Carbon dioxide.
Carbon dioxide is a naturally occurring gas in the atmosphere. It is produced by the respiration of plants and animals, as well as by the burning of fossil fuels. While carbon dioxide is a greenhouse gas and can contribute to climate change, it is not considered to be an air pollutant in the same way as other gases, such as sulfur dioxide and nitrogen oxides.
Sulfur dioxide is a gas that is released into the atmosphere when fossil fuels are burned. It can cause respiratory problems, such as asthma and bronchitis, and can also damage crops and forests.
Nitrogen oxides are gases that are released into the atmosphere when fossil fuels are burned. They can cause respiratory problems, such as asthma and bronchitis, and can also contribute to the formation of ground-level ozone.
Hydrocarbons are a group of organic compounds that are found in natural gas, gasoline, and other petroleum products. They can be released into the atmosphere when these products are burned. Hydrocarbons can contribute to the formation of ground-level ozone.