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: Radiology
[{'content': "Lead pipe appearance is seen in \nSelect and explain. \nA. Chron's disease, B. Ulcerative colitis, C. Schistosomiasis, D. Carcinoma colon", 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Ulcerative colitis', 'role': 'assistant'}]