This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'Which one of the following is the most characteristic arrhythmia with digitalis toxicity ? \nSelect and explain. \nA. Atrial fibrillation, B. Extrasystoles, C. NPAT with block, D. Auricular flutter', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]