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
90% of Brain growth is achieved by the ___________ 
Select and explain. 
A. 2nd year, B. 3rd year, C. 5th year, D. 15th year
B: 3rd year
Answer: B: 3rd year 
Explanation: Total brain volume at age 1 mo is approximately 36% of adult volume but by age 1 yr is approximately 72% (83% by 2 y).90% by 3 years of age. Ref.nelson 20th edition pg 65