Which of the following describes a rule that ensures ethical behavior among agents?

The choice indicating that agents must not practice unethical acts is essential in ensuring ethical behavior within the industry. This rule underscores the fundamental principle of integrity, which is crucial in maintaining trust between agents and their clients. By adhering to ethical standards, agents foster a professional environment where clients can expect honesty, transparency, and respect.

Ethical behavior includes honest representation of products, maintaining client confidentiality, and avoiding conflicts of interest, all of which build a solid foundation for client-agent relationships. This adherence to ethics not only protects clients but also upholds the reputation of the industry as a whole.

The other options suggest practices that undermine ethical standards. Prioritizing sales over service could lead to neglecting clients' best interests. False advertising misleads consumers, violating trust and legal regulations. Selling without proper licensing poses significant risks to clients and compromises the professionalism required in the field. Thus, the emphasis on not engaging in unethical acts is vital for fostering an ethical culture among agents.