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': 'In treatment of papillary carcinoma thyroid, radioiodine destroys the neoplastic cells predominantly by: \nSelect and explain. \nA. X-rays, B. ri rays, C. 7 rays, D. a paicles', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. ri rays', 'role': 'assistant'}]