What is being violated if two brokers agree to decrease their commission rates to 5.5% at the same time?

The situation described involves two brokers colluding to decrease their commission rates simultaneously, which constitutes a violation of anti-trust laws. These laws are designed to promote competition and prevent practices that restrain trade, such as price-fixing.

When brokers agree to set a specific rate, they are restricting their ability to compete freely in the marketplace. This kind of agreement can lead to higher prices for consumers as it eliminates competition, which anti-trust laws aim to prevent. Therefore, this scenario directly undermines the competitive nature of the real estate market and is a clear infringement of anti-trust regulations.

In contrast, options related to real estate laws, consumer protection laws, and agency laws do not specifically address the collusion aspect of commission rates, making them less relevant in this context. Anti-trust laws specifically target the anticompetitive practices exhibited by the brokers in this scenario, making it the correct answer.