Answer:
C. It blocks atrioventricular (AV) node conduction.
Step-by-step explanation:
Digoxin is a medication commonly used to treat atrial fibrillation with rapid ventricular response. It works by slowing down the conduction of electrical impulses through the atrioventricular (AV) node, which helps to control the heart rate in patients with atrial fibrillation. This effect makes it useful in reducing high ventricular rates associated with atrial fibrillation. It does not directly convert atrial fibrillation to sinus rhythm (Option B) or increase atrial contractility (Option A).