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: Dental
[{'content': 'Growth activity at which of these synchondroses completes first? \nSelect and explain. \nA. Spheno-occipital, B. Intersphenoidal, C. Intra-occipital, D. Sphenoethmoidal', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]