This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and breast, Subject name: Surgery
[{'content': 'Initial preferred investigation for thyroid nodule is: \nSelect and explain. \nA. FNAC, B. Radionucleide test, C. Thyroid function test, D. USG', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Initial investigation done in STN is thyroid function test(TFT) Investigation of choice in STN for diagnosis is FNAC Solitary Thyroid Nodule: Initial investigation done in STN is thyroid function test (TFT) If TFT is raised, next investigation is thyroid scan , (For hot nodules, RAI ablation or surgery is done; For warm or cold nodules follow-up or surgery) If TFT is normal, USG is done (Aspiration in cystic lesion, FNAC for solid or heterogenous lesions) Investigationn of choice in STN for diagnosis is FNAC. Ref: Sabiston 20th edition Pgno: 890', 'role': 'assistant'}]