<prompt> Adolescent stas at the age of?7 years10 years14 years17 years  <response>: Adolescence: Stage of transmission from childhood to adulthood. During this stage, there will be an appearance of sexual characters with changes in cognition and psychology. Adolescence refers to this entire process, pubey refers to the physical aspect. Age 10-19 year is considered as a period of adolescence and pubey marks the early half of adolescence. Pubey in girls stas with breast development thelarche anytime between 8-13 years. This is followed by an appearance of pubic hair pubarche and subsequently menstruation menarche, occurring at an average of 12.6 years. Menarche occurs after 2-212 years of thelarche. In boys, the earliest change is an increase in testicular size testicular volume reaching 4 ml and this occurs between 9-14 years. This is followed by an appearance of pubic hair and lengthening of the penis. Spermarche sperm production stas during mid-adolescence. Laryngeal growth, manifesting as cracking of voice, begins in boys in mid-pubey, deepening of voice is complete by end of pubey. During pubey, boys gain 20-30 cm and girls 16-28 cm of height. Peak growth velocity in girls occurs before attainment of menarche. Boys have their peak growth in later stages of pubey. Reference: GHAI Essential pediatrics, 8th edition 