Which of the following statements does NOT pose a potential antitrust liability?

The statement "I promote all of my listings" does not pose a potential antitrust liability because it refers to an individual's business practice regarding promoting their properties without making any agreements or proposals that restrict competition. This statement reflects a personal marketing strategy that does not imply collusion or an attempt to manipulate market conditions.

In contrast, the other statements involve agreements or practices that can suppress competition or manipulate market terms. For example, suggesting that a multiple listing service (MLS) won't accept listings below a certain duration can indicate a common practice that could indirectly lead to anti-competitive behavior. Additionally, declaring a standardized rate charged by every firm may suggest price-fixing, which is a blatant violation of antitrust laws. Lastly, stating that cooperation from other agents is contingent upon accepting certain terms could imply coercive tactics that stifle competition. These factors make the other statements more problematic from an antitrust perspective, whereas promoting one's listings alone does not convey any restriction or collusion in the market.