A nurse is reinforcing teaching with a client who is to start taking methotrexate to treat rheumatoid arthritis. Which of the following instructions should the nurse include in the teaching?

A. Methotrexate can cause renal toxicity. Encouraging fluid intake of at least 2 L/day helps prevent kidney damage and promotes drug excretion, making this the correct instruction. B. Commercial mouthwashes often contain alcohol, which can worsen methotrexate-induced stomatitis. Instead, clients should use a soft toothbrush and nonalcoholic rinses. C. Methotrexate for rheumatoid arthritis is taken weekly, not daily. Daily dosing can lead to severe toxicity. D. Foods high in vitamin K affect warfarin therapy, not methotrexate. There is no restriction on vitamin K with methotrexate use.