This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
[{'content': 'Mechanism of action of digitalis in atrial fibrillation is \nSelect and explain. \nA. By Causing bradycarlia, B. Na+ K+ ATPase inhibition, C. Increase in refractoriness of AV nodal tissue, D. By Causing bradycarlia', 'role': 'user'}, {'content': 'Answer: C \nExplanation: (Ref: KDT 6/ep502) Digitalis acts in CHF by inhibiting Na+-K+-ATPase whereas in AF, it acts by decreasing the conduction through AV node.', 'role': 'assistant'}]