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: Skin
[{'content': 'Nikolsky sign is positive in all of the following except: \nSelect and explain. \nA. Staphylococcal scalded skin syndrome, B. Toxic epidermonecrolysis, C. Bullous pemphigoid, D. Pemphigus', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C. i.e. Bullous pemphigoid', 'role': 'assistant'}]