Puberty usually begins earlier in girls than in boys.

The correct option is A

earlier

Puberty is the period during which growing boys or girls undergo the process of sexual maturation. The onset of puberty varies among individuals. Puberty usually occurs in girls between the ages of 10 and 14, while in boys it generally occurs later, between the ages of 12 and 16. Even though girls reach adolescence earlier, by the time boys are 18 to 19 years old, they catch up and reach their adult stature.