**Core Concept**
In cases of primary amenorrhea, particularly when secondary sexual characteristics are present, the focus shifts from identifying a primary cause to evaluating potential underlying conditions that may be contributing to the amenorrhea. This assessment involves a comprehensive approach, considering factors such as hormonal imbalances, anatomical abnormalities, and genetic disorders.

**Why the Correct Answer is Right**
When secondary sexual characteristics are present, it indicates that the individual has undergone puberty, suggesting the presence of estrogen. However, the absence of menstruation (primary amenorrhea) indicates a potential issue with ovulation or the uterine environment. Screening in this scenario should focus on conditions that may be affecting the hypothalamic-pituitary-ovarian axis, such as polycystic ovary syndrome (PCOS), congenital adrenal hyperplasia, or androgen excess disorders. The presence of secondary sexual characteristics helps to narrow down the differential diagnosis and guides further evaluation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not applicable as it does not provide a specific age or criterion for screening.
**Option B:** This option may be considered for cases without secondary sexual characteristics, as it is more relevant to identifying underlying anatomical or genetic causes.
**Option C:** This option is not specific and may not accurately reflect the optimal timing for screening in cases of primary amenorrhea with secondary sexual characteristics.

**Clinical Pearl / High-Yield Fact**
When evaluating primary amenorrhea, particularly in the presence of secondary sexual characteristics, it's essential to consider the possibility of polycystic ovary syndrome (PCOS) as a common underlying condition. PCOS is characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovaries, and its diagnosis can be challenging due to its variable presentation.

**Correct Answer: B. 14 years**