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
Stereotactic radiosurgery uses all except – 
Select and explain. 
A. Proton, B. Electron, C. Linear accelerator, D. Gamma knife
B: Electron
Answer: B: Electron 
Explanation: Stereotactic radiosurgery uses :- (i) Ca - 60 (Gamma knife); (it) X-ray knife (Linear accelerator); (iii) Cyclotron (Proton beam).