The correct answer is: 3. King believes some tension is necessary, Lincoln calls for unity.
In "The Gettysburg Address," Lincoln emphasizes unity and the importance of coming together as a nation, especially in the face of division caused by the Civil War. On the other hand, in "Letter from Birmingham Jail," King discusses the necessity of tension and disruption in the fight against injustice, arguing that nonviolent protest is a crucial part of achieving social change and equality.