Final answer:
The nurse should implement a low-sodium diet for a client with chronic kidney failure and elevated sodium levels.
Step-by-step explanation:
In this case, the nurse should implement Option 4: Administer a low-sodium diet.
Chronic kidney failure can result in electrolyte imbalances, including high levels of sodium and potassium.
By implementing a low-sodium diet, the nurse can help to reduce the elevated sodium level in the client's body and promote better overall kidney function.