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
[{'content': 'A child can laugh aloud at the age of:- \nSelect and explain. \nA. 2 months, B. 4 months, C. 6 months, D. 9 months', 'role': 'user'}, {'content': 'Answer: B \nExplanation: A child laughs aloud at the age of 4 month. 1 month - ales to sound 2 months - Vocalizes 3 months - Coos 4 months - Laughs aloud', 'role': 'assistant'}]