Which of the following statements about the timing and tempo of sexual maturation is true?
A) In the United States, and in all other countries, menarche typically occurs around age 12.
B) Adolescents who begin puberty earlier usually grow to be taller adults.
C) The duration of puberty varies widely, from 1.5 to 6 years in girls and 2 to 5 years in boys.
D) Adolescents who begin puberty early also complete it early.