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
Investigation of choice for congenital hypertrophic pyloric stenosis is? 
Select and explain. 
A. Barium meal, B. Ultrasound, C. CT scan, D. MRI
B: Ultrasound
Answer: B: Ultrasound 
Explanation: b. Ultrasound(Ref: Nelson's 20/e p 1797-1799, Ghai 8/e p 279-280)USG confirms the diagnosis of congenital hypertrophic pyloric stenosis