Which of the following foods can become contaminated and cause an infection by Staphylococcus aureus?

The correct choice is the food item that is most commonly associated with Staphylococcus aureus contamination. Ready-to-eat deli meats can easily become contaminated because they are often handled by food service employees during preparation and service. This bacterium is particularly resilient and can survive on surfaces; it produces toxins that can cause illness even when the bacteria itself is no longer present.

Deli meats are frequently served without cooking, which means that if they have been contaminated at any point during the handling process, they can directly lead to foodborne illness. The timing of handling and the temperature at which they are stored also play critical roles in the potential for contamination.

While raw fish, boiled eggs, and frozen desserts can also be sources of foodborne illness, they are less commonly linked specifically to Staphylococcus aureus. Raw fish is more often associated with other pathogens such as Vibrio or parasites. Boiled eggs, if cooked properly and handled safely, carry a lower risk of contamination by this bacterium. Frozen desserts, depending on their ingredients, generally have different spoilage microorganisms and mechanisms of contamination. Therefore, ready-to-eat deli meats stand out as the most notable risk factor for infection by Staphylococcus aureus.