A client taking warfarin (Coumadin) should be instructed to avoid herbal supplements such as green tea, ginkgo, feverfew, garlic, and ginger because these could:

The correct answer is A: Increase the risk for bleeding. Warfarin is an anticoagulant medication that works by inhibiting blood clotting. Herbal supplements like green tea, ginkgo, feverfew, garlic, and ginger can also have blood-thinning effects, potentially increasing the risk of bleeding when combined with warfarin. This interaction can lead to serious consequences such as excessive bleeding or bruising. It is crucial to avoid these supplements to prevent dangerous complications. Choices B, C, and D are incorrect because they do not directly relate to the potential interaction between warfarin and herbal supplements.