This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastro Intestinal System, Subject name: Pediatrics
[{'content': 'The metabolic derangement in congenital pyloric stenosis is: \nSelect and explain. \nA. Hypochloremic alkalosis, B. Hyperchloremic alkalosis, C. Hyperchloremic acidosis, D. Hypochloremic acidosis', 'role': 'user'}, {'content': "Answer: A \nExplanation: a. Hypochloremic alkalosis(Ref: Nelson's 20/e p 1797-1799, Ghai 8/e p 279-280)High Yield Points:Congenital Hypertrophic Pyloric StenosisIt is the commonest surgical disorder of the stomach during infancyMore common in boys and in infants of blood group 'B' and 'O'; Usually does not present at birth, but after 3 weeks ageNon-billious vomiting is the initial symptoms of pyloric stenosis; leads to Hypochloremic metabolic alkalosis", 'role': 'assistant'}]