Which of the following is a definition of primary amenorrhea?

The mean age of menarche became younger during this century. Therefore, the definition of primary amenorrhea changed:Primary amenorrhea is defined as the absence of menses by 13 years of age when there is no visible development of secondary sexual characteristics or by 15 years of age in the presence of normal secondary sexual characteristics. The ages defining primary amenorrhea were decreased by 1 year to continue to represent two standard detions above the mean age of developing secondary sexual characteristics and menses.Reference: Berek and Novak's gynecology; 14th edition; Chapter 30; Amenorrhea