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': 'Typical "Saw-tooth" colon on barium enema is seen with – \nSelect and explain. \nA. Colonic diverticulosis, B. Colonic volvulus, C. Colonic carcinoma, D. Ulcerative colitis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]