What situation occurs when a seller offers unjustified special prices or services to some customers but not others?

When a seller offers unjustified special prices or services to some customers but not others, it is an example of price discrimination. This practice occurs when different prices are charged to different customers for the same product or service, without a valid rationale for the price variation. Price discrimination can be used to maximize a seller's profits by capturing consumer surplus—charging customers based on their willingness to pay.

This concept can manifest in various forms, such as offering discounts based on customer demographics, time of purchase, or purchase volume. It is important to note that price discrimination is often regulated by laws, as it can lead to unfair competition and exploitation of certain groups of consumers.

In contrast, the other choices—price fixing, market segmentation, and contract breach—refer to different concepts within pricing strategies and legal agreements. Price fixing relates to colluding with competitors to set prices at a certain level, market segmentation involves dividing a market into distinct groups of consumers, and contract breach pertains to failing to adhere to the terms agreed upon in a contract, rather than the context of pricing discrepancies among customers.