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': 'A normally growing child smiles back (social smile) at the following age? \nSelect and explain. \nA. 2-4 weeks, B. 4-6 weeks, C. 6-8 weeks, D. 6-10 weeks', 'role': 'user'}, {'content': 'Answer: C \nExplanation: SOCIAL AND ADAPTIVE MILESTONES: 2 months: social smile (smile after being talked to). 3 months: Recognizes mother, anticipates feeds. 4 months: Holds rattle when placed in hand and regards it. Laughs aloud. Excited at the sight of food. 6 months: recognizes strangers, stranger anxiety. Enjoy watching own image in the mirror, shows displeasure when toy pulled off. 9 months: waves bye bye 12 months: comes when called, plays a simple ball game. Kisses the parent on request. Makes postural adjustments for dressing. 15 months: jargon, stas imitating mother. 18 months: copies parents in tasking, dry by day, points to three pas of the body on request. 2 years: ask for food, drink, toilet, pulls people to show toys. 3 years: shares toys, know full name and gender, dry by night. 4 years: Plays cooperatively in a group, goes to the toilet alone, washes face, brushes teeth. Roleplay. 5 years: helps in the household task, dresses, and undresses Ref: Ghai Essential Pediatrics, Ninth Edition, pg no. 48.', 'role': 'assistant'}]