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': 'Normal width of PDL is: \nSelect and explain. \nA. 0.5mm, B. 1. mm, C. 1.5mm, D. 2. mm', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]