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: Half life of cobalt - 60 is 5.2 years.