The nurse is teaching a client with atrial fibrillation about the need to begin long-term anticoagulant therapy. Which explanation should the nurse use to best describe the reasoning for this therapy?

A Because of the dysrhythmia, blood backs up in the legs and puts you at risk for blood clots.' B Because the atria are quivering, blood flows sluggishly through them, and clots can form along the heart wall, which then could loosen and travel to the lungs or brain.' C The medications that you are taking cause blood clots as a side effect so you need this medication to prevent them.'