This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skin Lesions And Disorders Of Pigmentation, Subject name: Skin
[{'content': 'Twelve-year-old boy with vesicle over lip. Investigation to be done is: \nSelect and explain. \nA. KOH mount, B. Tzank smear, C. Diascopy, D. Woods lamp', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. b. Tzanck smearHerpes labialis occurs due to HSV-I injection on Tzanck smear shows, multinucleated giant cells (MNGC).', 'role': 'assistant'}]