Generally the earliest age at which puberty begins is:

• A. 13 years in girls, 13 years in boys
• B. 11 years in girls, 11 years in boys
• C. 10 years in girls; 12 years in boys
• D. 12 years in girls, 10 years in boys

Answer: (C)

Puberty starts when the brain signals the gonads to increase sex hormone production, leading to the physical changes of adolescence. In girls, estrogen triggers the earlier onset of puberty, with breast development often the first visible sign, while in boys the first changes come from testosterone, typically a bit later. On average, puberty begins around 10 years in girls and about 12 years in boys, reflecting that girls usually start earlier. This is why the option listing 10 years for girls and 12 years for boys best fits the common pattern. There is wide individual variation, but the general trend is girls earlier than boys by roughly a couple of years. The other choices don’t align with that typical pattern.