A 34-year-old woman at 35 weeks' gestation is admitted with a persistent blood pressure of 172/114 mmHg, a severe headache, and 3+ proteinuria. She has a history of moderate persistent asthma requiring daily inhaled corticosteroids. Magnesium sulfate is started for seizure prophylaxis. Which of the following is the most appropriate acute antihypertensive choice, and what is the delivery plan?