Which of the following is prohibited in advertisements by licensees?

Using the Texas state seal in advertisements by licensees is prohibited because it can imply an official endorsement or affiliation with the state government, which is misleading and could mislead the public regarding the legitimacy or regulatory status of the services offered. This prohibition helps maintain the integrity of state symbols and ensures that advertisements do not convey false messages about the nature of the business being conducted.

In contrast, including a website link, mentioning past accomplishments, and using customer testimonials are generally accepted practices in advertising, provided they are truthful and not misleading. These elements can help to effectively showcase the credibility and reliability of a business while providing potential customers with more information.