A nurse is teaching a client who has a prescription for warfarin. Which of the following statements by the client indicates an understanding of the teaching?

A. St. John's wort can decrease the effectiveness of warfarin, so it should be avoided. B. Using a hard bristle toothbrush could cause gum bleeding in clients taking warfarin and should be avoided. C. INR should be checked regularly, not just once a year, to monitor the therapeutic range for warfarin. D. There is no known interaction between cantaloupe and warfarin.