This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Growth and development, Subject name: Pediatrics
[{'content': 'This social milestone is established by age of ___________ \nSelect and explain. \nA. 1 month, B. 2 months, C. 3 months, D. 4 months', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Babies establish a smile on social contact by 2 months. Also done at 2 months Head sustained in a plane of the body on ventral suspension Follows moving object by 180 degrees Smiles on social contact Listen to voices and coos Ref : Nelson 20th edition pg no : 67', 'role': 'assistant'}]