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': 'Full bowel preparation is avoided in all, except ? \nSelect and explain. \nA. Carcinoma colon, B. Hirschprung disease, C. Ulcerative colitis, D. Irritable bowel syndrome', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is None or 'a' i.e., Carcinoma colon", 'role': 'assistant'}]