The correct answer is A) emotional appeal.
The type of appeal that President Lincoln used in this excerpt is an emotional appeal.
When President Abraham Lincoln expresses in his First Inaugural Address that "We are not enemies but friends. We must not be enemies," he was using an emotional appeal to try to convince his audience.
You use Ethos or an ethical appeal when you use to convince through your experience, character or credibility. You use Pathos or the emotional appeal when you try to use emotion to convince your audience. And you use Logos when yo use the logic or the reason to support your arguments.