Which of the following is a trademark?

A trademark is defined as a distinctive word, symbol, or design that identifies and distinguishes the source of the goods of one party from those of others. This legal protection allows businesses to secure their brand identity and prevents others from using similar marks that could cause confusion in the marketplace.

While unique product designs and advertising slogans can have their own forms of intellectual property protection (such as trade dress for design and copyright for slogans), they do not meet the strict legal definition of a trademark. Retail strategies, on the other hand, are more related to the business model and tactics used to sell products rather than identifying the source of those products. Therefore, the most accurate choice that aligns with the definition of a trademark pertains to distinctive words or symbols.