A 78-Year-Old Female Patient Was Recently Diagnosed with Atrial Fibrillation

A 78-year-old female patient was recently diagnosed with atrial fibrillation and started on Coumadin (warfarin) for stroke prophylaxis. A nurse provides extensive education on warfarin including the need for routine blood testing. The woman states the following to a nurse: "I understand all that you have taught me, but I do not know what a good number for the INR test is." The nurse bases her response on the knowledge that the recommended INR is:

A) 1.0-2.0.
B) 2.0-3.0.
C) 3.0-4.0.
D) 4.0-5.0.