This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Impoant Motor Milestones, Subject name: Pediatrics
[{'content': 'What is the sequence in which the following milestones are attained? \nSelect and explain. \nA. A - B - C - D, B. C - B - A -D, C. D - C - B - A, D. C - B - D - A', 'role': 'user'}, {'content': 'Answer: D \nExplanation: A - Ties shoe laces -5 years B - Copies circle - 3 years C - Feeds self with spoon - 18 months D- Buttons & unbuttons - 4 years', 'role': 'assistant'}]