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': 'Investigation of choice for Pseudo - obstruction \nSelect and explain. \nA. Barium enema, B. CECT, C. Water soluble contrast enema, D. Colonoscopy', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]