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': 'The commonest bladder stone is \nSelect and explain. \nA. Triple phosphate, B. Xanthine, C. Uric acid, D. Cysteine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: IInd MC vesical calculi → Sturvite stones', 'role': 'assistant'}]