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
The half life of Cobalt -60 is 
Select and explain. 
A. 3.4 years, B. 5.2 years, C. 1.2 years, D. 2.3 years
B: 5.2 years
Answer: B: 5.2 years 
Explanation: B i.e. 5.2 years