A 68-year-old with atrial fibrillation is taking warfarin as part of therapy for the prevention of thromboembolic event. His goal INR is 2-3, which is checked monthly and has been within acceptable range for the past 6 months. Today he presents with an INR=3.8. He denies bleeding events and reports, “I am taking my medicine just like I was told.” The NP considers that:A. The INR should be repeated today.B. A single dose of injectable vitamin K should be ordered.C. His health history sho...