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': 'In smokers the incidences of periodontal disease are: \nSelect and explain. \nA. 2-6 times, B. 6-10 times, C. 10-14 times, D. No effect', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]