Which of the following illustrates a method of bacterial transmission via contaminated food?

Eating raw vegetables illustrates a method of bacterial transmission via contaminated food because these vegetables can carry pathogenic bacteria if they are not properly washed or cooked. Contamination can occur at various points in the food supply chain, from agricultural practices to handling and preparation. Consuming raw or undercooked foods increases the risk of ingesting harmful bacteria, which could lead to foodborne illnesses.

The other options do not directly relate to the transmission of bacteria through food. Allergies to bacteria refer to immune reactions rather than transmission methods. The use of antibiotics primarily concerns treatment rather than transmission, as antibiotics are used to combat bacterial infections. Vaccination against pathogens is a preventive measure to protect against infections and does not involve direct transmission through food.