What must be true when advertising a specific number of motor vehicles?

When advertising a specific number of motor vehicles, it is essential that they must be invoiced to the dealer. This requirement is crucial because it ensures that the vehicles being advertised are officially accounted for in the dealer's inventory. Having the vehicles invoiced provides a level of assurance to customers that the vehicles are genuinely part of the dealer's stock and that the dealer has the right to sell them.

Invoicing indicates that the dealer has legally obtained the vehicles, which is necessary to facilitate sales and maintain transparency in the transaction process. If vehicles are not invoiced to the dealer, there is a risk that they may not be available for sale when a customer inquires, leading to potential dissatisfaction and trust issues.

While the other options may seem plausible, they do not adhere to the important regulations surrounding vehicle advertising. For instance, vehicles being in transit doesn't guarantee that they are available to customers at the time of advertising, and being sold at any price disregards pricing regulations that aim to protect consumers. Additionally, advertising vehicles that aren’t physically available or invoiced could mislead consumers and result in legal repercussions for the dealership. Thus, having the vehicles invoiced is a fundamental requirement for ethical and legal advertising practices in the motor vehicle industry.