According to the Environmental Protection Agency (EPA), which one of the following is the largest source of sulphur dioxide emissions?

According to the Environmental Protection Agency (EPA) and various international environmental agencies, the largest source of sulphur dioxide (SO₂) emissions globally, and certainly in countries with significant fossil fuel reliance, is **D) Power plants using fossil fuels**, particularly coal-fired power plants. Coal often contains a significant amount of sulfur. When coal is burned for electricity generation, this sulfur is released as sulfur dioxide. While other sources like industrial processes (including metal smelting/extraction), ships, and locomotives do contribute to SO₂ emissions, the sheer scale of fossil fuel combustion in power generation (especially coal) makes it the dominant source. * **Locomotives using fossil fuels:** Contribute, but not the largest source. * **Ships using fossil fuels:** While maritime shipping is a major source of SO₂ emissions, especially from heavy fuel oil, it is generally secondary to large power plants on a global scale. * **Extraction of metals from ores (Smelting):** Smelting processes, especially of sulfide ores, can release substantial amounts of SO₂, but again, typically less than coal-fired power generation on a national or global scale. Therefore, power plants using fossil fuels are the largest source.