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
Which iodine isotope is used for the treatment of carcinoma of thyroid? 
Select and explain. 
A. Iodine 131, B. Iodine 123, C. Iodine 213, D. All of the above
A: Iodine 131
Answer: A: Iodine 131 
Explanation: The initial treatment for cancer of the thyroid is surgical. A consensus approach might be to perform a total thyroidectomy if the primary tumor is larger than 1 cm in diameter or if there is extra-thyroidal involvement or distant metastases. Clinically evident lymphadenopathy should be removed with a neck dissection. If the primary tumor is less than 1 cm in diameter, a unilateral lobectomy might be considered.
About 4-6 weeks after surgical thyroid removal, patients must have radioiodine to detect and destroy any metastasis and any residual tissue in the thyroid.