Final answer:
The nurse should recommend eggs to a lactating client as the best source of protein. They contain all essential amino acids, making them a complete protein source. Other high-protein food recommendations include beans, chicken, and dairy products.
Step-by-step explanation:
The nurse should recommend eggs as the best source of protein for a lactating client looking to increase their intake. Eggs are a complete protein, containing all the essential amino acids required by the body, and are especially good for nursing mothers. Other examples of high-protein foods include beans, chicken, peanut butter, steak, and dairy products. On the other hand, spinach, while healthy, provides less protein content compared to eggs, and white bread is generally less rich in protein. Soda does not contain protein and therefore is not a useful recommendation for increasing protein intake.