A patient with supraventricular tachycardia is prescribed a beta-blocker. Which of the following physiological effects is primarily responsible for its antiarrhythmic action in this scenario?

✓ Correct Answer: Option B

Beta-blockers reduce heart rate and decrease conduction velocity through the AV node by blocking beta-1 receptors. This action prolongs the refractory period, making it effective in controlling supraventricular tachycardias.