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
Most commonest bladder stone is 
Select and explain. 
A. Ammonium urate, B. Uric acid, C. Struvite, D. Calcium oxalate
B: Uric acid
Answer: B: Uric acid 
Explanation: MC primary bladder stone - ammonium urate
MC secondary bladder stone - uric acid (MC overall).