**Core Concept**
Preeclampsia is a pregnancy complication characterized by high blood pressure and signs of damage to another organ system, most often the liver and kidneys. The definitive treatment of preeclampsia involves stabilizing the mother and delivering the baby, as the condition typically resolves after delivery.

**Why the Correct Answer is Right**
The definitive treatment of choice in this patient is delivery, as preeclampsia is a pregnancy-specific condition that resolves postpartum. The American College of Obstetricians and Gynecologists (ACOG) recommends delivery at 34 weeks of gestation or later if the mother's condition is stable. Delivery is the definitive treatment as it addresses the root cause of the condition, which is the placenta. The placenta produces substances that cause blood vessels to constrict, leading to high blood pressure and end-organ damage. Removing the placenta through delivery resolves the condition.

**Why Each Wrong Option is Incorrect**
**Option A:** Corticosteroids are used to promote fetal lung maturity in cases of preterm labor, but they are not the definitive treatment for preeclampsia.
**Option B:** Antihypertensive medications may be used to manage high blood pressure in preeclampsia, but they do not address the underlying cause of the condition and are not the definitive treatment.
**Option C:** Bed rest is not a recommended treatment for preeclampsia, as it has not been shown to improve outcomes and may actually increase the risk of complications.

**Clinical Pearl / High-Yield Fact**
The "HELLP" syndrome is a variant of preeclampsia characterized by hemolysis, elevated liver enzymes, and low platelet count. It is a serious complication that requires immediate delivery.

**Correct Answer:** D. Delivery. Delivery is the definitive treatment of choice for preeclampsia, as it addresses the root cause of the condition, which is the placenta.