Answer:The rhetorical appeal that an author uses when establishing credibility by referencing an authority is called ethos. Ethos is one of the three main rhetorical appeals, along with pathos (emotional appeal) and logos (logical appeal). Ethos refers to the author's credibility, expertise, and trustworthiness. By referencing an authority, the author is using ethos to enhance their own credibility and persuade the reader to trust their argument or viewpoint.
Step-by-step explanation:
hope it helps