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': 'Isotope for thyroid scaning – a) I129b) I131c) Technetium99d)  Selenium \nSelect and explain. \nA. bc, B. c, C. ac, D. ad', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Isotopes used for thyroid scanning are 1234 131, and technetium - 99m pertechnate. \n\tNote - Some books have given II" also. But it is not used for thyroid scintigraphy.', 'role': 'assistant'}]