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': 'Flower vase appearance on IVP is seen in: \nSelect and explain. \nA. Horseshoe kidney, B. Polycystic kidney, C. Pyonephrosis, D. Congenital megaureter', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Horseshoe kidney', 'role': 'assistant'}]