A nurse is completing an admission assessment for a client who has been taking St. John's wort. The nurse should identify that which of the following medications can interact with St. John's wort?

A. "Rifampin": While it can interact with many medications by increasing their metabolism and reducing their effectiveness, it is not the primary or most clinically significant interaction typically associated with St. John's Wort. B. "Furosemide": Furosemide is a diuretic used for fluid retention. While St. John's wort may interact with certain medications, it does not have a known significant interaction with furosemide. C. "Citalopram": St. John's Wort induces cytochrome P450 enzymes, increasing the metabolism of citalopram, which can decrease its effectiveness and increase the risk of serotonin syndrome. D. "Allopurinol": Allopurinol is used to treat gout, and there is no significant interaction between it and St. John's wort.