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': "Nikolsky's sign is positive in \nSelect and explain. \nA. Pemphigus, B. Dermatitis herpatiformis, C. Pemphigoid, D. Rubella", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]