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
[{'content': 'Principle used in radiotherapy is \nSelect and explain. \nA. Cytoplasmic coagulation, B. Ionization of molecule, C. DNA damage, D. Necrosis of tissue', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. ionization of molecule', 'role': 'assistant'}]