This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'Discoloration and accelerated wear is seen in composite restoration, if a patient is using a toothpaste having: \nSelect and explain. \nA. Stannous flouride, B. Calcium carbonate, C. Chloroform, D. Both 2 and 3', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Calcium carbonate is a surface abrasive and causes wear.\nChloroform causes softening of the composite matrix and causes discoloration.', 'role': 'assistant'}]