**Core Concept**
Polycystic Ovary Syndrome (PCOS) is a complex endocrine disorder characterized by ovulatory dysfunction, hyperandrogenism, and polycystic ovarian morphology. The hormonal imbalance in PCOS is primarily driven by an excess of androgens, which are produced by the ovaries and adrenal glands. The insulin resistance and hyperinsulinemia that often accompany PCOS further exacerbate the hormonal imbalance.

**Why the Correct Answer is Right**
The high FSH/LH ratio is not a characteristic of PCOS. Instead, PCOS is typically associated with an elevated LH level, often in the context of a normal or low FSH level. This hormonal imbalance leads to an excessive production of androgens, which contributes to the clinical manifestations of PCOS, such as hirsutism and acne. The high LH level also disrupts ovulation, resulting in anovulatory cycles and irregular menstrual periods.

**Why Each Wrong Option is Incorrect**
**Option B:** Bilateral ovarian cysts are not a defining feature of PCOS. While cysts may be present on the ovaries, they are not a universal finding in PCOS patients. Polycystic ovarian morphology, characterized by multiple small cysts, is a more specific diagnostic criterion.
**Option C:** Hirsutism is indeed a common symptom of PCOS, resulting from the excess androgen production. However, the high FSH/LH ratio is not a characteristic of PCOS, making option A the correct answer.
**Option D:** Increased risk of diabetes mellitus is a known complication of PCOS, primarily due to the insulin resistance and hyperinsulinemia that often accompany the disorder.

**Clinical Pearl / High-Yield Fact**
PCOS is a heterogeneous disorder, and its diagnosis can be challenging. The Rotterdam criteria, which define PCOS as the presence of at least two of the following three features: ovulatory dysfunction, hyperandrogenism, and polycystic ovarian morphology, have improved diagnostic accuracy.

**✓ Correct Answer: A. High FSH/LH ratio**