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: Medicine
[{'content': 'All of the following are true of atrial fibrillation EXCEPT \nSelect and explain. \nA. Occurs in rheumatic mitral stenosis, B. May cause thromboembolic complications, C. Pulse is irregularly irregular, D. Associated with sinus bradycardia', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]