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': 'Not a Radiological sign of Ulcerative colius \nSelect and explain. \nA. Raspberry appearance, B. Toxic megacolon, C. Lead Pipe appearance, D. Pseudopolyps', 'role': 'user'}, {'content': "Answer: A \nExplanation: Raspberry / rose thorm appearance is seen in crohn's disease.", 'role': 'assistant'}]