This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2019, Subject name: Surgery
[{'content': '32-year man presented with fever and pain in upper right hypochondrium after food intake. Investigation of choice; \nSelect and explain. \nA. CECT, B. Ultrasound, C. MRI, D. HRCT', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ultrasound is Investigation of choice for Gall stone Acute cholecystitis Acute acalculous cholecystitis Chronic cholecystitis', 'role': 'assistant'}]