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
[{'content': 'Investigation of choice for congenital hypertrophic pyloric stenosis is? \nSelect and explain. \nA. Barium meal, B. Ultrasound, C. CT scan, D. MRI', 'role': 'user'}, {'content': "Answer: B \nExplanation: 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", 'role': 'assistant'}]