Which practice is considered a violation of federal antitrust laws?

Setting pricing for services with competitors is a clear violation of federal antitrust laws because it constitutes price-fixing. Price-fixing occurs when businesses within the same industry agree on the prices they will charge for services, which ultimately restricts competition and harms consumers by eliminating the natural price fluctuations that would occur in a competitive market.

Antitrust laws are designed to promote fair competition and prevent monopolistic practices that can lead to higher prices and reduce choices for consumers. When real estate companies collude to set prices, they undermine these principles, effectively eliminating competition among them. This is why option B is a violation; it directly disrupts the market's ability to function freely and fairly.

In contrast, the other practices listed do not inherently inhibit competition in the same way. Refusing commissions based on unethical practices maintains ethical standards without interfering with competition. Discussing commission rates openly can be done legally, as long as it does not lead to coordinated pricing strategies. Informing clients about service options is a fundamental part of providing good customer service and does not control or manipulate pricing in any way.