This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pharynx, Subject name: ENT
[{'content': 'Tonsils reach their maximum size by \nSelect and explain. \nA. 1 year, B. 3 years, C. 5 years, D. 12 years', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Tonsils are most active from 4 to 10 years of age. Involution begins after pubey resulting in a decrease of B-cell production and a relative increase in the ratio of T to B cells. (Ref: Diseases of Ear, Nose and Throat, PL Dhingra; 7th edition ,pg no. 292)', 'role': 'assistant'}]