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
[{'content': 'Congenital hypertropic pyloric stenosis is diagnosed by – \nSelect and explain. \nA. CT, B. USG, C. MRF, D. X-ray', 'role': 'user'}, {'content': 'Answer: B \nExplanation: USG is the investigation of choice for CHPS', 'role': 'assistant'}]