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
What is the following most characteristic feature of congenital hyperophic pyloric stenosis? 
Select and explain. 
A. The patient is commonly marasmic, B. It is associated with early loss of appetite, C. It mostly affects the first born female child, D. The pyloric tumour is best felt during feeding
D: The pyloric tumour is best felt during feeding
Answer: D: The pyloric tumour is best felt during feeding 
Explanation: Diagnosis of congenital hyperophic pyloric stenosis can be made with a test feed, which produces a characteristic peristaltic wave which is seen to pass across the upper abdomen. Palpation of the abdomen at that time reveals the lump. Ref: Bailey and Love's Sho Practice of Surgery, 24th Edition, Page 1033.