The correct answer is answer "C," when an author uses ethos to persuade readers, they are trying to gain the audience's trust. Ethos is an appeal to ethics, character, or credibility.
The author may use personal anecdotes, examples of their expertise or qualifications, or references to respected sources to establish themselves as trustworthy and credible. By doing so, they aim to convince the readers that their arguments and claims are reliable and worthy of consideration.
For example, an author writing about climate change might mention that they have a PhD in environmental science and have conducted extensive research in the field. This would help to establish their credibility and make readers more likely to trust their perspective on the issue.
It is important to note that using ethos alone is not sufficient to fully persuade readers. Authors also typically use other persuasive techniques, such as logos (appealing to logic and reason) and pathos (appealing to emotions), to strengthen their argument.
I hope this helps you. :)