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': 'Most sensitive phase in cell division to radiation is \nSelect and explain. \nA. G1 phase, B. G2 phase, C. S phase, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]