You respond to a mottled, cyanotic 3-month-old, 5-kg infant who responds only to painful stimuli. Proximal pulses are too rapid to count and thready proximally. Distal pulses are absent. The skin is pale and cold distally. Capillary refill is 5 seconds. Respirations are 65/min, and the patient is working hard to breathe. ECG shows a narrow complex tachycardia with no P waves visible. You should:

a. administer oxygen and transport.
b. cardiovert at 0.5 to 1 J/kg.
c. administer verapamil.
d. administer 20 mL/kg lactated Ringer's solution.

b