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': 'Radiation mediates its effect by \nSelect and explain. \nA. Denaturation of DNA, B. Ionization of the molecules, C. Protein coagulation, D. Osmolysis of cells', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Denaturation of DNA', 'role': 'assistant'}]