A 30-year-old man with type 1 diabetes presents to the emergency department (ED). His blood pressure (BP) is 100/70 mm Hg and heart rate (HR) is 140 beats per minute. His blood glucose is 750 mg/dL, potassium level is 5.9 mEq/L, bicarbonate is 5 mEq/L, and arterial pH 7.1. His urine is positive for ketones. Which of the following is the best initial therapy for this patient?

a. Give normal saline as a 2-L bolus; then administer 20 units of regular insulin subcutaneously.

b. Bolus 2 ampules of bicarbonate and administer 10 units of insulin intravenously.

c. Give him 5 mg of metoprolol to slow down his heart, start intravenous (IV) hydration, and then give 10 units of regular insulin intravenously.

d. Give normal saline in 2 L bolus and then administer 10 units of insulin intravenously followed by an insulin drip and continued hydration.

e. Give normal saline in 2 L bolus with 20 mEq/L potassium chloride (KCl) in each bag.