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': 'Unilateral hydronephrosis is due to ? \nSelect and explain. \nA. Bladder neck contracture, B. Stricture urethra, C. Carcinoma of prostate, D. All', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. is c i.e. Carcinoma prostate', 'role': 'assistant'}]