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: Dental
[{'content': 'Period of adolescent growth in boys is: \nSelect and explain. \nA. 3 years, B. 3.5 years, C. 4 years, D. 5 years', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Key Concept:\nThe stages of sexual development in boys are more difficult to specifically define than in girls. Puberty begins later and extends over a longer period-about 5 years compared with 3 1/2 years for girls.\nAdolescent Growth Stages Versus Secondary Sexual Characteristics:\nGirls:\nTotal Duration of Adolescent Growth: 3 ½\xa0 years\xa0\nStage 1\xa0\nBeginning of adolescent growth\xa0\n\nAppearance of breast buds, initial pubic hair.\n\nStage 2 (About 12 months later)\nPeak velocity in height\xa0\n\nNoticeable breast development, axillary hair, darker and more abundant pubic hair.\n\nStage 3 (12-18 months later)\nGrowth spurt ending\n\nMenses, broadening of hips with adult fat distribution, breasts completed.\n\nBoys:\nTotal Duration of Adolescent Growth: 5 years\nStage 1\xa0\nBeginning of adolescent growth\n\n“Fat spurt” weight gain, feminine fat distribution.\n\nStage 2 (About 12 months later)\nHeight spurt beginning\xa0\n\nRedistribution and reduction in fat, pubic hair, growth of penis.\n\nStage 3 (8-12 months later)\nPeak velocity in height\xa0\n\nFacial hair appears on upper lip only, axillary hair, muscular growth with harder, more angular body form.\n\nStage 4 (15-24 months later)\nGrowth\xa0spurt ending\xa0\n\nFacial hair on chin and lip, adult distribution and color of public and axillary hair, adult body form.\n\nRef: Contemporary orthodontics Proffit 6th ed\xa0 page 150', 'role': 'assistant'}]