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
Cobalt 60 is: 
Select and explain. 
A. Naturally occurring radioisotope, B. Aificial radioisotope, C. Product of plutonium, D. Product of uranium
B: Aificial radioisotope
Answer: B: Aificial radioisotope 
Explanation: Ans. Aificial radioisotope