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: Radiology
Investigation of choice for diagnosis of congenital hyperophic pylori stenosis: 
Select and explain. 
A. USG, B. Barium meal, C. Barium meal follow through, D. CT scan with contrast
A: USG
Answer: A: USG 
Explanation: Ans. USG