Final answer:
Raw seafood can cause a food-borne illness.
Step-by-step explanation:
The nurse should instruct the client that raw seafood can cause a food-borne illness. Raw seafood, such as oysters, can be contaminated with bacteria like Salmonella, Vibrio, and Campylobacter, which can lead to foodborne illnesses. It is important for the client to avoid consuming raw seafood and opt for cooked seafood instead.