This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
[{'content': 'Cellular content of DNA is doubled in \nSelect and explain. \nA. S phase, B. M phase, C. G1 phase, D. G2 phase', 'role': 'user'}, {'content': 'Answer: A \nExplanation: .', 'role': 'assistant'}]