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': 'Clinical signs of gingivitis appear in \nSelect and explain. \nA. Initial gingivitis, B. Early gingivitis, C. Late gingivitis, D. Advanced gingivitis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]