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': 'Management of 5 cm size renal struvite calculus \nSelect and explain. \nA. ESWL, B. PCNL, C. Retrograde intrarenal surgery, D. Open Pyelolithotomy', 'role': 'user'}, {'content': 'Answer: B \nExplanation: For stones which are\n\n>2cm size\nHydronephrosis\nObstructed\n\nPCNL is performed', 'role': 'assistant'}]