This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vesiculobullous (Blistering) Disorders, Subject name: Skin
[{'content': "Characteristic feature of pemphigus vulgaris: \nSelect and explain. \nA. Sub epidermal bullae, B. Acantholysis, C. Negative Nikolsky's sign, D. Bullae on erythematous base", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. b. AcantholysisSubepidermal bullae on erythematous base with negative Nikolsky sign is seen in bullous pemphigoid', 'role': 'assistant'}]