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': 'Most common type of renal stone is: March 2013 (d) \nSelect and explain. \nA. Calcium phosphate, B. Magnesium ammonium phosphate, C. Cystine, D. Uric acid', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A i.e. Calcium Phosphate', 'role': 'assistant'}]