How does acid rain primarily damage buildings?

Acid rain primarily damages buildings by reacting with calcium carbonate in stone. Many historical buildings and structures are made from limestone and marble, which are largely composed of calcium carbonate. When acid rain, which contains sulfuric and nitric acids, falls on these materials, a chemical reaction occurs. This reaction produces soluble compounds that can wash away, leading to the gradual erosion and weakening of the stone. Over time, this degradation can significantly impair the structural integrity and aesthetic appearance of the building.

The other options do not accurately reflect the primary mode of damage caused by acid rain. While acidic fumes can indeed corrode metals, the main damage from acid rain specifically relates to its interaction with calcium carbonate. Physical erosion from precipitation can occur, but it is not as significant a factor as the chemical reaction taking place. Lastly, while the growth of mosses might be a consequence of damp conditions, it is not a direct effect of acid rain.