Trademark - a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or services from those of other entities.
Trade dress - characteristics of the visual appearance of a product or its packaging (or even the design of a building) that signify the source of the product to consumers.
Design patent - a patent granted on the ornamental design of a functional item. Design patents are a type of industrial design right. Ornamental designs of jewelry, furniture, beverage containers (see Fig. 1) and computer icons are examples of objects that are covered by design patents.
Trademark is the least correct of the three in this case.