Here's why:

* Source: Sulfur dioxide is primarily released from the burning of fossil fuels (coal, oil, and natural gas) in power plants and industrial processes.

* Atmospheric Reactions: In the atmosphere, sulfur dioxide reacts with oxygen and water to form sulfuric acid (H2SO4).

* Acid Rain Formation: Sulfuric acid, along with nitric acid (formed from nitrogen oxides), dissolves in rainwater, making it acidic.

While nitrogen oxides (NOx) also contribute to acid rain, sulfur dioxide is considered a major contributor due to its widespread release from industrial activities.