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
The metabolic derangement in congenital pyloric stenosis is: 
Select and explain. 
A. Hypochloremic alkalosis, B. Hyperchloremic alkalosis, C. Hyperchloremic acidosis, D. Hypochloremic acidosis
A: Hypochloremic alkalosis
Answer: A: Hypochloremic alkalosis 
Explanation: 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