Final answer:
Mahatma Gandhi effectively used ethos and pathos, utilizing his credibility and emotional appeals, to persuade his audience, particularly in his 'Quit India' speech.
Step-by-step explanation:
The rhetorical device Gandhi uses most effectively in persuading his audience is ethos, which is the presentation of a believable, authoritative voice that elicits credibility and trust from the audience. Gandhi's reputation as a leader and his moral authority gave him a powerful ethical appeal to his listeners. Additionally, Gandhi used pathos by appealing to the emotions of his audience, evoking feelings of patriotism, duty, and the emotional weight of suffering under colonial rule. While Gandhi also employed logos, presenting logical arguments for independence and the effectiveness of nonviolent resistance, it was his ethos and pathos that were most resonant and persuasive to his audience, as seen in his speeches, and particularly in his "Quit India" speech.