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 highest ionizing potential – 
Select and explain. 
A. X–ray, B. Gamma ray, C. α–rays, D. β–rays
C: α–rays
Answer: C: α–rays 
Explanation: Penetration power : Gamma rays> X rays > Beta particle >Alpha particle (or helium ion) Ionizing & damaging power: is reserve Alpha particle (or helium ion) > Beta particle > X ray> Gamma ray