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
Renal calculi associated with proteus infection 
Select and explain. 
A. Uric acid, B. Triple phosphate, C. Calcium oxalate, D. Xanthine
B: Triple phosphate
Answer: B: Triple phosphate 
Explanation: Triple phosphate or struvite( Calcium phosphate with ammonium magnesium phosphate ) is smooth and diy white, grows in alkaline medium. Proteus being urea splitting organism splits urea to give ammonium which provides the required alkaline medium. Reference : page 1292 Bailey and Love's sho practice of surgery 26th edition