What is one requirement for a dealer plate to be used?

A dealer plate is specifically designed to facilitate the testing and transportation of vehicles by licensed dealers. One key requirement for the use of a dealer plate is that it may be utilized while the vehicle is in a dealer's shop for repairs. This allows the dealership to move or test vehicles that are undergoing maintenance without needing to register and plate each vehicle individually, which streamlines operations.

In this context, using the dealer plate in a repair shop context emphasizes the practical aspect of dealership operations, where vehicles are regularly maintained or serviced. This requirement supports the dealer's business activities by providing the flexibility needed to operate efficiently within the bounds of regulations.

As for the other options, they either limit the scope of the dealer plate usage incorrectly or misinterpret the intended use of these plates in a commercial context. For example, dealer plates are not restricted to only new vehicles or for transfers solely between dealers, and personal use by a dealer's family is not an appropriate use for dealer plates given that they are meant for business purposes.