Which one of the following is the main cause of the acid rain ?

Acid rain is primarily caused by the emission of sulfur dioxide (SO2) and nitrogen oxides (NOx) into the atmosphere [1][3]. While natural sources like volcanoes and rotting vegetation contribute small amounts, the vast majority of these pollutants result from human activities, specifically the burning of fossil fuels in power plants, industrial processes, and motor vehicles [1]. Once released, these gases undergo chemical transformations, reacting with water, oxygen, and other atmospheric chemicals to form sulfuric and nitric acids [3]. These acids then mix with precipitation, lowering the pH of rain, snow, or fog to levels typically below 5.6 [4]. Carbon dioxide also contributes by forming weak carbonic acid, but the strong acidity associated with environmental damage is driven by sulfur and nitrogen oxides released during fossil fuel combustion [4].

Sources

1. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > Acidification > p. 8
2. [3] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > 5.I5. ACID RAIN > p. 101
3. [4] https://www.nationalgeographic.com/environment/article/acid-rain