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: Unknown
[{'content': 'Basioccipital basisphenoid will fuse at: \nSelect and explain. \nA. 21-25 years, B. 35-45 years, C. 25-30 years, D. 30-40 years', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref. Textbook of forensic medicine. Krishnan Vij. Page.42', 'role': 'assistant'}]