<prompt> Tonsils reach their maximum size by1 year3 years5 years12 years  <response>: 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 