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
Most harmful to individual cell : 
Select and explain. 
A. X-rays, B. a - paicles, C. b - paicles, D. X- rays (gamma rays)
B: a - paicles
Answer: B: a - paicles 
Explanation: B i.e. a - paicles