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
Which of the following has longer half life: March 2009 
Select and explain. 
A. I-123, B. I-131, C. I-132, D. All have equal half life
B: I-131
Answer: B: I-131 
Explanation: Ans. I-131