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
Social smile is attained at what age ? 
Select and explain. 
A. 2 months, B. 5 months, C. 9 months, D. 1 year
A: 2 months
Answer: A: 2 months 
Explanation: None