Which of the following are not major sources of sulfur dioxide pollution?

The identification of electrical substations as not being a major source of sulfur dioxide pollution is accurate because they primarily function to transform and distribute electrical energy rather than to produce emissions. Sulfur dioxide, a harmful air pollutant, is predominantly released from sources that combust sulfur-containing fuels, which is typical in electric power plants, chemical manufacturing facilities, and transportation systems.

Electric power plants, particularly those utilizing coal and oil, are significant contributors to sulfur dioxide emissions due to the combustion process. Similarly, chemical manufacturing can produce sulfur dioxide as a byproduct of various chemical reactions involved in producing industrial chemicals. Transportation emissions, particularly from vehicles that burn fossil fuels, also contribute notably to sulfur dioxide pollution.

In contrast, electrical substations do not engage in combustion processes; their operational role is to manage the distribution of electricity, making them a negligible source of sulfur dioxide emissions compared to the other options listed. This understanding illustrates the nature of emissions connected to different types of facilities and emphasizes the importance of identifying the primary sources of environmental pollutants.