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': '90% of Brain growth is achieved by the ___________ \nSelect and explain. \nA. 2nd year, B. 3rd year, C. 5th year, D. 15th year', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 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', 'role': 'assistant'}]