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': 'Ionization radiation acts on tissue leading to \nSelect and explain. \nA. Linear acceleration injury, B. Excitation of electron from orbit, C. Formation of pyramidine dimer, D. Thermal injury', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Excitation of electron from orbit', 'role': 'assistant'}]