A 35-year-old male presents with sudden onset palpitations, lightheadedness, and shortness of breath. ECG shows a regular, narrow-complex tachycardia at a rate of 180 bpm with no discernible P waves. He is hemodynamically stable. What is the most appropriate initial management?

✓ Correct Answer: Option C

For stable narrow-complex tachycardia, adenosine is the first-line pharmacologic agent. It transiently blocks AV nodal conduction, often terminating re-entrant pathways causing supraventricular tachycardia. Other options are for unstable patients or different types of arrhythmias.