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: Surgery
[{'content': 'Investigation of choice in discrete thyroid swelling is- \nSelect and explain. \nA. Isotope scans, B. Ultrasonography, C. Autoantibody titers, D. FNAC', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]