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': 'High or low fistula in ano is termed according to its internal opening present with reference to - \nSelect and explain. \nA. Anal canal, B. Dentate line, C. Anorectal ring, D. Sacral promontory', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]