This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'Social smile is attained at what age ? \nSelect and explain. \nA. 2 months, B. 5 months, C. 9 months, D. 1 year', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]