This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thyroid, Subject name: Surgery
36 year old lady was diagnosed with Papillary carcinoma thyroid , total thyroidectomy was done but whole body iodine scan came out to be positive . What should be the next step in management ? 
Select and explain. 
A. Re-exploration, B. Radio-iodine ablation, C. USG-neck, D. Bi-annual follow-up
B: Radio-iodine ablation
Answer: B: Radio-iodine ablation 
Explanation: Radio Active Iodine Ablation I 131 emits beta- rays (90%) and gamma- rays (10%) Beta rays are responsible for therapeutic effects Depth of penetration of beta rays -0.5 mm(Ablates only thyroid, even parathyroids are safe) Gamma rays are responsible for side effects Indications of RAI Ablation Elderly Patients Patient with surgical co-morbidities Recurrence after surgery Absolute contraindication(because gamma rays are emitted) Pregnancy Lactation