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': 'A 85 year old woman with Nikolsky sign–ve, blisters on thigh & trunk, lesions come on & off. What is the cause – \nSelect and explain. \nA. Pemphigus vulgaris, B. Pemphigoid, C. Lichen planus, D. Dermatitis herpetiformis', 'role': 'user'}, {'content': "Answer: B \nExplanation: In this question :-\n\n\nAge\xa0→\xa085 year\nBlisters on lower body (thigh & trunk)\nNikolsky's sign negative\n\n\nAmongst the given options only pemphigoid (bullous pemphigoid) full fills these criteria.", 'role': 'assistant'}]