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': 'Which of the following has longer half life: March 2009 \nSelect and explain. \nA. I-123, B. I-131, C. I-132, D. All have equal half life', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. I-131', 'role': 'assistant'}]