This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Radiotherapy Pa 2, Subject name: Radiology
Most ionizing radiation among the following is? 
Select and explain. 
A. X rays, B. Gamma rays, C. Alpha rays, D. Beta rays
C: Alpha rays
Answer: C: Alpha rays 
Explanation: Alpha rays have the highest ionization power, whereas gamma rays have the highest penetration power.