**Core Concept**
Exposure of a female fetus to excess androgens during early embryogenesis can disrupt the normal development of the urogenital sinus, leading to the formation of a male-like external genitalia in females. This process is known as virilization.

**Why the Correct Answer is Right**
During embryogenesis, the urogenital sinus is a critical structure that gives rise to the female external genitalia, including the labia and clitoris. The presence of androgens, such as testosterone, can stimulate the growth and differentiation of the urogenital sinus, leading to the development of male external genitalia. This is because the urogenital sinus is sensitive to androgenic stimulation, and excess androgens can override the normal female developmental pathway. In contrast, the Mullerian ducts, ovaries, and mesonephric ducts are not directly affected by androgen exposure in the same way.

**Why Each Wrong Option is Incorrect**
**Option A:** Mullerian ducts are responsible for the development of the female internal reproductive organs, including the fallopian tubes, uterus, and upper part of the vagina. They are not affected by androgen exposure and are not responsible for the formation of external genitalia.

**Option B:** The ovaries are responsible for producing sex hormones, including estrogen, which promotes female development. They are not directly affected by androgen exposure and are not responsible for the formation of external genitalia.

**Option D:** Mesonephric ducts are a pair of embryonic structures that give rise to the male internal reproductive organs, including the epididymis, vas deferens, and seminal vesicles. They are not directly involved in the formation of external genitalia and are not affected by androgen exposure in the same way as the urogenital sinus.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that excess androgen exposure during embryogenesis can lead to virilization of female external genitalia, resulting in a range of anomalies, including clitoromegaly, labial fusion, and urogenital sinus anomalies. This can occur due to a variety of causes, including congenital adrenal hyperplasia, androgen-secreting tumors, and exposure to androgenic substances during pregnancy.

**✓ Correct Answer: C. Urogenital sinus**