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 cause of metabolic alkalosis is ? \nSelect and explain. \nA. Cancer stomach, B. Pyloric stenosis, C. Small-bowel obstruction, D. Diuretics', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Pyloric stenosis", 'role': 'assistant'}]