Under what condition may Illinois licensees advertise a property for sale?

In Illinois, real estate licensees must have the owner's permission to advertise a property for sale, which is why the correct choice is that the owner has given written permission. This requirement helps protect both the rights of the property owner and the integrity of the advertising process. When a licensee has written consent, it establishes a clear agreement regarding advertising, ensuring that the owner is informed and agrees to the terms under which their property will be marketed.

Having written permission not only affirms the owner’s approval but also minimizes the risk of potential disputes regarding unauthorized advertisements. This regulation maintains ethical standards in real estate transactions, ensuring that all parties are aware of and agree to how the property is being represented in the market.

While other options might seem plausible—such as personal interest or type of listing—they do not meet the necessary legal requirements for advertising without explicit owner consent. Thus, the owner's written permission is imperative for any advertising to proceed legally and ethically.