The statement explaining the purpose of ethos is D. It references an authority to appear credible to the audience.
This is known to be a characteristic spirit used to describe the guiding beliefs and ideals of a community or nation.
Ethos is a greek word meaning for 'character' and is today used to refer to practices or values which distinguish a person or organization from another.
Ethos uses character, credibility and ethics to persuade, hence, the best explanation for the purpose of ethos is that it references an authority to appear credible to the audience.
Therefore, the correct answer is option D.
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