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
True regarding atrial fibrillation -a) ↑ Thromboembolismb) Digoxin treatmentc) Anticoagulant not requiredd) Aspirin given 
Select and explain. 
A. acd, B. abd, C. abc, D. ab
B: abd
Answer: B: abd 
Explanation: None