This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Social and Language Milestones, Subject name: Pediatrics
A child has staed mouthing objects, shows likes and dislikes, but has not yet developed stranger anxiety. The age of child is: 
Select and explain. 
A. 3 months, B. 5 months, C. 7 months, D. 9 months
B: 5 months
Answer: B: 5 months 
Explanation: Stranger anxiety, that develops at around 7 months has not yet appeared. So, the age of the child is 5 months. Child stas mouthing object: 5-6 months.