Which of the following is an example of a cross-connection?

The correct choice is a sink without an air gap. A cross-connection occurs when there is a direct link between a safe drinking water supply and a potentially contaminated source. This is a critical concern in food safety and public health, as cross-connections can lead to backflow, allowing contaminants to enter the potable water supply.

In this context, a sink without an air gap represents a violation of safe plumbing practices. An air gap is a physical separation between the end of a water supply outlet and the flood level of a fixture, which prevents any backflow from occurring. Without this air gap, there is potential for contaminants from the sink to enter the water supply, thereby creating a cross-connection.

Examining the other options: a hose in a mop bucket does not create a direct contamination risk unless there are specific conditions leading to backflow. A faucet attached to a garden hose could pose a contamination risk, but the presence of an air gap would typically negate that concern. A drinking fountain does not represent a cross-connection as it is designed to provide safe drinking water without direct contact with contaminated sources. Thus, the emphasis on the necessity of the air gap directly correlates to the definition and dangers associated with cross-connections in food service and public