A foodborne illness outbreak has been confirmed when:

A foodborne illness outbreak is confirmed when two or more individuals experience the same illness after consuming the same contaminated food. This ensures that the incident is not just an isolated case, but rather indicates a pattern that suggests the food in question is a common source of illness.

When only one person falls ill, it could be due to a variety of individual factors unrelated to an outbreak, such as personal allergies or pre-existing health conditions. The presence of contaminated food items alone does not confirm an outbreak; the actual impact on multiple individuals is necessary to establish a link between the food and the illness. Similarly, the scenario where no illnesses are reported yet food samples test positive lacks evidence of actual sickness, which is crucial for declaring an outbreak. Therefore, the confirmation of an outbreak hinges on multiple cases stemming from a shared food source, making the second option the most accurate description of the situation.