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 of these is a definitive treatment for  Gravae thyrotoxicosis? 
Select and explain. 
A. Carbimazole, B. Sterioid, C. Hemithyroidectomy, D. Radioiodine
D: Radioiodine
Answer: D: Radioiodine 
Explanation: None