Which of the following describes a sound trademark?

A sound trademark refers to a distinctive sound that identifies and distinguishes the products or services of one entity from those of others. The correct choice highlights that certain sounds can uniquely represent a business and serve as a way to identify its brand. A sound that is trademarked must meet specific criteria, including distinctiveness and non-functionality, allowing consumers to associate that sound specifically with a particular source.

When considering the context of the other options, sound trademarks do not typically encompass sounds that represent both products and services, as clarity in representation is crucial for establishing distinctiveness. Additionally, while many sounds are indeed used in advertising, not all advertising sounds qualify for trademark protection since they may not be distinctive enough. Universal sounds that are not trademarked do not serve the purpose of a trademark, which is to denote the source of a specific product or service; they do not provide any brand identity. Thus, the choice that emphasizes the representation of a business through sound captures the essence of what constitutes a sound trademark.