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': 'Rectal polyp most commonly presents as- \nSelect and explain. \nA. Obstruction, B. Bleeding, C. Infection, D. Changes into malignancy', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]