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': 'True regarding atrial fibrillation -a) ↑ Thromboembolismb) Digoxin treatmentc) Anticoagulant not requiredd) Aspirin given \nSelect and explain. \nA. acd, B. abd, C. abc, D. ab', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]