What scenario illustrates a one-to-many relationship?

A one-to-many relationship occurs when one entity in a relationship can be associated with multiple instances of another entity. In this scenario, the correct illustration of a one-to-many relationship is where several workers share a single telephone extension. This indicates that one telephone extension (the "one" side) can be linked to multiple workers (the "many" side), clearly demonstrating that a single instance (the phone extension) can relate to multiple occurrences (the workers using it).

To further clarify the other scenarios: when a single student is enrolled in multiple classes, it depicts a many-to-many relationship, as one student can be associated with many classes, and classes can have many students enrolled. The situation where each employee has a unique office phone demonstrates a one-to-one relationship because each employee is linked to only one distinct office phone. Lastly, stating that each flight has one aircraft suggests a one-to-one relationship as well, where each flight corresponds to a single aircraft, rather than illustrating the capacity for multiple flights to connect to one aircraft.