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: Radiology
[{'content': "'Flower vase' appearance on intravenous urogram is seen in \nSelect and explain. \nA. Duplex system with upper moeity ureterocele, B. Polycystic kidney disease, C. Horse-shoe kidney, D. Retro-caval ureter", 'role': 'user'}, {'content': 'Answer: C \nExplanation: .', 'role': 'assistant'}]