The correct answer is 3. Logical appeal
Step-by-step explanation:
In persuasion there are different appeals or strategies a speaker can use to convince or persuade the audience about an idea, in the case of logical appeal, this appeal uses arguments based on reasoning and facts, because of this it is common to rely on evidence such as official documents, statistics, research studies, among others. In the case of Lincoln's speech he refers to the law and especially to the Constitution of the U.S. to state Southern states could not secede as the Constitution implied "no government proper ever had a provision in its organic law for its own termination". Therefore, in this case, Lincoln is mainly using arguments based on reasoning and facts as he referred to an official document and therefore, the technique used to persuade Southerners is mainly a logical appeal.