Which of the following best defines a complete unit appliance?

A complete unit appliance is defined as one that comprises all the necessary components to function independently without the need for additional external equipment or controls. This includes the burner for combustion, controls for operation and safety, and integral wiring that connects these components, allowing the appliance to operate seamlessly as a single unit.

In this context, the correct choice highlights the comprehensive nature of a complete unit appliance. It signifies that all critical elements, which are integral to its operational capability, are contained within the appliance itself, ensuring that it can be installed and utilized effectively without requiring supplemental elements.

Other options detail aspects that do not align with this definition. For instance, an appliance supplied with external controls lacks the self-contained operational characteristics that define a complete unit. Additionally, an appliance requiring separate wiring suggests that it is not fully integrated, differentiating it from a complete unit. Lastly, an appliance intended solely for display does not fit the functioning criteria of a complete unit, as it serves no practical purpose beyond aesthetics.