Concept:Stone cancer is the discoloration and damage of stone surfaces caused by acid rain.Explanation:Acid rain contains pollutants like sulfur dioxide and nitrogen oxides.These pollutants react chemically with the calcium carbonate in marble and stone.This reaction causes the stone surface to corrode, discolor, and develop a rough texture.The Taj Mahal in India is a famous example of stone cancer.Its white marble has turned yellowish due to constant exposure to acid rain.Answer:C. Acid rain