The nurse is caring for a patient receiving warfarin and notes bruising and petechiae on the patient's extremities.The nurse will request an order for which?

Choice A rationaleChecking vitamin K levels doesn't directly monitor warfarin's effect.Choice B rationalePTT and aPTT assess heparin, not warfarin.Choice C rationaleINR specifically measures warfarin's effectiveness and safety.Choice D rationalePlatelet levels don't monitor the anticoagulant effect of warfarin.