A nurse is caring for a client who is prescribed cyclosporine following a kidney transplant. The nurse should instruct the client that which of the following foods can increase cyclosporine levels to a toxic level?

A. Orange juice: Orange juice does not interact significantly with cyclosporine and is generally safe for clients taking this medication. B. Smoked salmon: While high in protein and sodium, smoked salmon does not affect cyclosporine metabolism or increase the risk of toxicity. C. Grapefruit juice: Grapefruit juice inhibits the CYP3A4 enzyme system in the liver and intestines, which metabolizes cyclosporine. This interaction leads to increased drug levels in the blood, raising the risk of nephrotoxicity and other toxic effects. D. Bananas: Bananas are not known to interact with cyclosporine. However, clients with kidney disease may need to monitor potassium intake, especially if potassium levels are already elevated.