This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
[{'content': 'For hiatus hernia, investigation of choice is not related-surgery \nSelect and explain. \nA. Barium meal follow through, B. Barium meal upper GI, C. Barium meal upper GI in Trendelenburg position, D. Barium meal double contrast', 'role': 'user'}, {'content': 'Answer: C \nExplanation: .', 'role': 'assistant'}]