<prompt> What is true regarding congenital hyperophic pyloric stenosis :More common in girlsHypochloremic alkalosisHellers myotomy is the procedure of choiceMost often manifests at bih  <response>: Hypochloremic alkalosis develops due to vomiting. Ref: Text Book of Pediatrics By Nelson, 19th Edition, Page 1274; Bailey and Loves Sho Practice of Surgery, 22nd Edition, Page 674 and 23rd Edition, Page 899. 