She denies chest pain or shortness of breath. Her lungs are clear to auscultation, has no jugular venous distention and no edema. A 12-lead ECG confirms a regular, narrow-complex tachyarrhythmia. Her blood pressure is 130/85 mmHg. What is your next action?
a) Administering a beta-blocker
b) Initiating thrombolytic therapy
c) Administering anticoagulants
d) Proceeding with synchronized cardioversion