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': "A young boy presented with a lesion over his right buttock which had peripheral scaling and central clearing with scarring. The investigation of choice would be: \nSelect and explain. \nA. Tzank smear, B. KOH preparation, C. Biopsy, D. Sabourad's agar", 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. Biopsy', 'role': 'assistant'}]