The correct answer is logo.
Rhetorical appeals are known by their names of ethos, pathos or logo.
They are means to persuade others to believe a particular point of view.
Logo ( appeals to logic ) is a way to persuade the audience with reason, using facts and figures.The facts and figures support the speaker's claim or thesis.
Clinton uses logo to enhance his credibility in this speech. By using numbers and examples, he makes this speech more believable to his audience, thus enhancing his own achievements.