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': '8 year old boy presented with boggy swelling on the scalp and easily pluckable hair. which of the following is the investigation of choice? \nSelect and explain. \nA. Biopsy, B. X ray skull, C. KOH smear, D. Tzank smear', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The diagnosis is tinea capitis hence investigation of choice is KOH smear.', 'role': 'assistant'}]