This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intersex, Subject name: Gynaecology & Obstetrics
A girl is said to have primary amenorrhea in absence of secondary sexual characters by what age: 
Select and explain. 
A. 13 years, B. 16 years, C. 14 years, D. 15 years
A: 13 years
Answer: A: 13 years 
Explanation: - The first sign of pubey is accelerated growth. - Breast budding is usually the first recognized pubeal change, followed by the appearance of pubic hair, peak growth velocity, and menarche. - Primary amenorrhea is defined as absence of menses at age 13 years when there is no visible development of secondary sexual characteristics or age 15 years in the presence of normal secondary sexual characteristics or have not attained menarche 5 or more years since the onset of pubeal development.