Dealer demo plates may be displayed on a vehicle under which condition?

The correct condition for displaying dealer demo plates is when a dealership employee is present with a prospective buyer. This requirement is in place to ensure that the vehicle is being demonstrated to a potential customer, allowing them to assess the vehicle's features and capabilities under the guidance of someone knowledgeable about the vehicle and the dealership's offerings.

Having a dealership employee present serves several purposes: it provides an immediate point of contact for answering questions, ensures compliance with regulations regarding the use of dealer plates, and helps maintain accountability for the vehicle's use. By limiting this practice to situations where an employee is present, it reinforces the professional standards expected in the sales process and enhances customer service.

The other conditions indicated in the incorrect options do not align with the regulations governing the use of dealer demo plates. For example, displaying demo plates at any time or during nighttime hours without the presence of a dealership employee could lead to misuse or misrepresentation of the vehicle's status. Similarly, using the plates for any vehicle regardless of ownership does not reflect the intended purpose of demonstrating vehicles that are part of the dealership's inventory.