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': 'To increase resistance form of an excessively tapered preparation: \nSelect and explain. \nA. Reduce height of preparation to shorten arc of rotation, B. Increase cervical reduction to taper, C. Add groove, D. Use adhesive cement', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]