**Core Concept**
Eclampsia is a severe complication of preeclampsia characterized by seizures in a pregnant woman, typically after 20 weeks of gestation. It requires immediate management to prevent maternal and fetal morbidity.

**Why the Correct Answer is Right**
The management of eclampsia involves stabilizing the mother, administering anticonvulsants to control seizures, and preparing for delivery. Magnesium sulfate is the preferred anticonvulsant due to its effectiveness in preventing seizures and its ability to cause muscle relaxation, which helps in controlling hypertension. Magnesium sulfate also has a neuroprotective effect, which is beneficial in preventing cerebral edema associated with eclampsia.

**Why Each Wrong Option is Incorrect**
**Option A:** Administering oxygen and monitoring vital signs is essential, but it is not the next step in managing eclampsia.
**Option B:** Although corticosteroids may be given to promote fetal lung maturity, they are not the primary management for eclampsia.
**Option C:** While delivery is ultimately necessary, it is not the immediate next step in managing eclampsia; stabilizing the mother and administering anticonvulsants take priority.

**Clinical Pearl / High-Yield Fact**
In eclampsia, magnesium sulfate is the preferred anticonvulsant, and its dosage should be adjusted according to the patient's response, as it can cause respiratory depression and cardiac arrest at toxic levels.

**Correct Answer: D. Administer magnesium sulfate.**