This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidney Stones & Renal Tubular Acidosis, Subject name: Medicine
[{'content': 'What is the investigation of choice for the ureteric stone? \nSelect and explain. \nA. CT scan, B. USG, C. MIBG scan, D. DMSA scan', 'role': 'user'}, {'content': 'Answer: A \nExplanation: All of the routine methods have become less useful with the advent of more sensitive and specific nonenhanced computed tomography (CT) scanning. When CT is available, it is now considered the examination of choice for the detection and localization of urinary stones.', 'role': 'assistant'}]