A nurse is reporting a client's laboratory tests to the provider to obtain a prescription for the client's daily warfarin. Which of the following laboratory tests should the nurse plan to report to obtain the prescription for the warfarin?

A. Fibrinogen level: Fibrinogen is involved in clot formation but is not used to monitor warfarin. B. INR: INR reflects the client’s clotting tendency and is essential for determining the appropriate warfarin dose. Therapeutic INR ranges typically vary based on the indication (e.g., 2.0–3.0 for atrial fibrillation). C. Platelet count: Important for assessing bleeding risk, but it does not measure warfarin's efficacy. D. aPTT: Used to monitor heparin therapy, not warfarin.