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
What is the sequence in which the following milestones are attained? 
Select and explain. 
A. A - B - C - D, B. C - B - A -D, C. D - C - B - A, D. C - B - D - A
D: C - B - D - A
Answer: D: C - B - D - A 
Explanation: A - Ties shoe laces -5 years B - Copies circle - 3 years C - Feeds self with spoon - 18 months D- Buttons & unbuttons - 4 years