Here's why:

* Acid rain is primarily composed of sulfuric and nitric acids. These acids react with the minerals in rocks, causing them to break down and erode.

* Quartzite is composed almost entirely of quartz. Quartz is a very hard and resistant mineral that is not easily affected by acid rain.

* Other types of rocks, like limestone and marble, are more susceptible to acid rain because they contain calcium carbonate, which readily reacts with acids.

Therefore, quartzite is the most resistant to acid rain among common rock types.