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': 'Purpose of cavity preparation is \nSelect and explain. \nA. To receive restorating material, B. To cleanse the caries, C. To remove bacteria, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]