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
NMR principle is based on 
Select and explain. 
A. Positron, B. Neutron, C. Proton, D. Electron
C: Proton
Answer: C: Proton 
Explanation: NMR/MRI principle is based on ability of protons in the body to absorb and emit radio waves when the body is placed in strong magnetic field