The rhetorical appeal which uses speaker credibility to persuade an audience is ethos. (option D)
What is ethos?
Ethos is an appeal to ethics whose efficacy depends on the credibility of the speaker. In other words, the listener will tend to trust a claim or argument when it's given by a specialist on the subject or, at least, some sort of role model.
Suppose you listen to your uncle Charles discuss vaccines at the dinner table. Uncle Charles is a man who believes in conspiracy theories and who distrusts science. Chances are that you will not be persuaded by his arguments.
On the other hand, if you hear a scientist who specializes in vaccines discussing the same topic, you will likely be convinced by his arguments. Here, there is ethos in play, that is, you see the speaker as credible.
Learn more about ethos here:
https://brainly.com/question/13118125
