Which difficult task did stalin most likely face when he tried to use ethos in his speech

B.) Since he had starved and tortured many soviets, he had to make himself seem trustworthy to his people

Ethos is an ethical appeal, which the speakers or writers use to persuade their audience. It'a a natural reaction for people to accept the credibility of someone they admire. Since this way of persuasion is based on character's credibility, it would be impossible for Stalin to use ethos in his speech, on a account of all his atrocities.