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': 'For a rectal carcinoma at 5cm from the anal verge the best acceptable operation is - \nSelect and explain. \nA. Anterior resection, B. Abdominal perineal resection, C. Posterior resection, D. Local resection', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Dentate line is 2 cm from the anal verge, so this tumor is 3 cm above the dentate line. A sphincter saving LAR can be done.', 'role': 'assistant'}]