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 to radiotherapy is: \nSelect and explain. \nA. G1, B. S, C. G2M, D. M', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. G2M', 'role': 'assistant'}]