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
Half life of Technetium 99 is: 
Select and explain. 
A. 2 hours, B. 6 hours, C. 12 hours, D. 24 hours
B: 6 hours
Answer: B: 6 hours 
Explanation: Ans. 6 hours