**Core Concept**
Congenital Adrenal Hyperplasia (CAH) is a group of inherited disorders that affect the adrenal glands, leading to impaired production of cortisol and aldosterone. This results in an overproduction of androgens, causing virilization in affected females.

**Why the Correct Answer is Right**
The prenatal treatment for CAH involves administering dexamethasone to the pregnant woman to suppress fetal adrenal androgen production. This is done to prevent virilization of female fetuses. The mechanism involves the transfer of dexamethasone across the placenta, where it inhibits the fetal adrenal gland's production of androgens.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to prenatal treatment of CAH.
**Option B:** This option is incorrect as it does not address the prenatal treatment of CAH.
**Option C:** This option is not the best prenatal treatment for CAH.

**Clinical Pearl / High-Yield Fact**
The key to effective prenatal treatment of CAH is early initiation of dexamethasone administration, ideally before 9 weeks of gestation, to prevent virilization of female fetuses.

**Correct Answer: D. Dexamethasone**