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: Pediatrics
During growth cycle of a child, usually at what age childhood ends and adolescence stas? 
Select and explain. 
A. 8 years, B. 10 years, C. 12 years, D. 16 years
B: 10 years
Answer: B: 10 years 
Explanation: WHO/UN definitions: Adolescent - 10-19 years Youth - 15-24 years Young people - 10-24 years Ref: Ghai essential pediatrics, 6th edition, Page 66.