How does sulfur dioxide contribute to the formation of acid rain?

Sulfur dioxide contributes to the formation of acid rain primarily through its ability to dissolve in rainwater and form sulfurous acid. When sulfur dioxide enters the atmosphere, it reacts with water droplets present in clouds, resulting in a chemical reaction that produces sulfurous acid.

This reaction initiates a series of processes in the atmosphere where sulfurous acid can further oxidize to form sulfuric acid. Both sulfurous acid and sulfuric acid are strong acids that can significantly lower the pH of rainwater, leading to the phenomenon known as acid rain.

While there may be some confusion with the other options, it's important to note that simply evaporating or combining with oxygen are not processes directly associated with the formation of acid rain in this context. The key mechanism driving acid rain involves the dissolution of sulfur dioxide in water and the subsequent chemical reactions that produce acidic compounds.