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
Condition which does not cause metabolic acidosis 
Select and explain. 
A. Renal failure, B. Pyloric stenosis, C. Biliary fistula, D. Ureterosigmoidostomy
B: Pyloric stenosis
Answer: B: Pyloric stenosis 
Explanation: Pyloric stenosis causes Metabolic alkalosis. Rest all causes metabolic acidosis.