This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fundamentals in Radiology, Subject name: Radiology
Which of the following is the most penetration beam 
Select and explain. 
A. Electron beam, B. 8 MeV Photons, C. 18 MeV Photons, D. Proton beam
C: 18 MeV Photons
Answer: C: 18 MeV Photons 
Explanation: Penetration power of photons depends on the kinetic energy. higher the kinetic energy of the photon beam,higher will be the penetration power. kVp determines the penetrating power of Xrays.