Which of the following must be conspicuously displayed in a dealer's place of business?

The correct choice emphasizes the importance of transparency and accountability in the automotive sales industry. Displaying the dealer's license in a conspicuous manner within the dealership is a legal requirement. This practice not only helps to ensure compliance with state regulations but also instills confidence in customers, as it signifies that the dealer is authorized to conduct business and operates within the legal framework.

Having the dealer's license prominently displayed serves as a verification of legitimacy and encourages trust among potential buyers. It allows customers to easily confirm that they are dealing with a registered and licensed entity, which is crucial in maintaining ethical standards within the industry.

In contrast, while vehicle inventories, promotional brochures, and customer testimonials can enhance the dealership's marketing efforts and provide useful information to customers, they do not carry the same legal significance as the dealer's license. The license serves a critical role in validating the dealership's operations and should be prioritized in terms of its visibility.