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
[{'content': 'NMR based in the principle of \nSelect and explain. \nA. Electron beam, B. Proton beam, C. Magnetic field, D. Neutron beam', 'role': 'user'}, {'content': 'Answer: D \nExplanation: NMR stands for Nuclear Magnetic Resonance. MRI is based on the ability of a small number of protons within the body to absorb and emit radio wave energy when the body is placed in the strong magnetic field.', 'role': 'assistant'}]