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': 'All of the following are significant risk factors for colonic carcinoma in an adenomatous polyp except \nSelect and explain. \nA. Pedunculated polyp, B. Villous histology, C. Size > 2 cm, D. Atypia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Adenomatous polyps may be sessile or pedunculated. Cancers develop more frequently in sessile polyps.\nAtypia, on histology, seen anywhere, is a risk factor for cancer.', 'role': 'assistant'}]