This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
A child can make a 3 cube tower at the age of : 
Select and explain. 
A. 36 months, B. 15 months, C. 20 months, D. 24 months
B: 15 months
Answer: B: 15 months 
Explanation: 15 months
Motor: Walks alone; crawls upstairs.
Adaptive:Makes tower of 3 cubes; makes a line with crayon; inserts raisin in bottle.
Language; Jargon; follows simple commands; may name a familiar object (e.g. ball).
Social: Indicates some desires or needs by pointing; hugs parents.