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: Surgery
[{'content': 'Internal sphincterotomy is the treatment of choice for - \nSelect and explain. \nA. Piles, B. Fistula, C. Fissure-in-ano, D. Carcinoma', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]