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': 'When the dental plaque is allowed to accumulate in the absence of any plaque control procedures, it results in gingivitis within \nSelect and explain. \nA. 1 to 3 days, B. 7 to 21 days, C. 2 months to 3 months, D. 24 hours to 48 hours', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]