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': "In which of the following conditions the lead pipe appearance of the colon on a barium enema is seen? \nSelect and explain. \nA. Amoebiasis, B. Ulcerative colitis, C. Tuberculosis of the colon, D. Crohn's involvement of the colon", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Ulcerative colitis', 'role': 'assistant'}]