This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
[{'content': 'Features of pyloric stenosis \nSelect and explain. \nA. Hypokalemic alkalosis, B. Peristalsis right to left, C. Commonly caused by carcinoma stomach, D. Retention vomiting present', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Because of vomiting-hypochloremia hyponatremia, hypocalcemia, hypomagnesemia alkalosis occurs. Reference: SRB edition:5th page no: 829', 'role': 'assistant'}]