D. Ethos. It is clearly the rhetorical device.
Ethos is based on the character of who is speaking or writing. It's how a person convinces the audience that he or she is prepared to talk about a specific subject. Thus linking dependence on the author's reputation (an appeal to the authority or honesty of the person that is speaking or writing). It's a persuasive strategy.
Ethos is a greek word which means "character"; therefore, it means persuading or convincing others using the character of the persuader. It is also related to the english word "ethics".
Ethos is one of the persuasion´s modes that are devices in rhetoric that classify the speaker's appeal to the public.