## Core Concept
Rokitansky-Küster-Hauser (RKH) syndrome, also known as Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, is a congenital disorder characterized by the absence or underdevelopment of the vagina and uterus. This condition is associated with normal ovarian function and normal secondary sexual characteristics.

## Why the Correct Answer is Right
The correct answer, ., is associated with Rokitansky-Küster-Hauser syndrome because the condition primarily involves the absence or underdevelopment of the Müllerian duct derivatives, which include the uterus, cervix, and upper part of the vagina. Individuals with RKH syndrome typically have normal ovaries and normal secondary sexual characteristics, indicating that the condition does not affect the development of the gonads or the production of sex hormones.

## Why Each Wrong Option is Incorrect
- **Option A:** is seen in RKH syndrome as it involves abnormalities in the development of the Müllerian duct derivatives.
- **Option B:** can be associated with RKH syndrome, as individuals may have normal ovarian function.
- **Option D:** is also a feature, as patients typically have normal secondary sexual characteristics due to normal ovarian function and hormone production.

## Clinical Pearl / High-Yield Fact
A key clinical pearl for RKH syndrome is that patients have a 46,XX karyotype, normal ovarian function, and normal secondary sexual characteristics, but they lack a uterus and often have vaginal hypoplasia. A classic association is with renal and skeletal anomalies.

**Correct Answer:** .