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': 'The investigation of choice for acute cholecystitis is – \nSelect and explain. \nA. USG, B. HIDA-Scan, C. CT-Scan, D. X-ray', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Investigation of choice for acute cholecystitis\xa0\xa0\xa0→\xa0USG\nMost accurate (best) method for diagnosis of acute cholecystitis\xa0→\xa0Radionuclide scan (DISIDA, PIPIDA, HIDA)', 'role': 'assistant'}]