This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urology, Subject name: Surgery
[{'content': '"Spider leg" deformity in excretory urogram occurs in \nSelect and explain. \nA. Hydronephrosis, B. Polycystic kidney, C. Uretrocele, D. Renal agenesis', 'role': 'user'}, {'content': "Answer: B \nExplanation: polycystic kidney, an autosomal dominant disease, common in females; excretory urogram shows 'spider leg' pattern - elongated and compressed renal pelvis with narrowed and stretched calyces over the cysts. ( Reference: emedicine.medscape.com/aicle/983281-workup )", 'role': 'assistant'}]