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 polyps usually present with - \nSelect and explain. \nA. Obstruction, B. Perforation, C. Bleeding, D. Malignant change', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]