Final answer:
True, a product can only display the ® symbol if its trademark is registered with the USPTO, as this ensures the brand's identity is legally protected and recognized.
Step-by-step explanation:
The statement that a product marketed in the United States can display the ® symbol only if the trademark has been registered with the United States Patent and Trademark Office (USPTO) is true. Trademarks are identifying symbols, names, or words that represent a company or product, establishing a brand's identity in the marketplace. The USPTO is responsible for granting patents and registering trademarks, ensuring that a firm's intellectual property is legally protected. Registration provides legal backing for a company to use the ® symbol, signifying that its trademark is officially recorded and recognized by the authorities. This registration process is in place to prevent confusion among consumers and to avoid infringement on someone else's trademark.