The correct answer is national unity.
This speech was given just one month before the official end of the American Civil War. This war caused significant fighting between the Union and the Confederacy. This war caused the deaths of thousands of American citizens on both sides. As this war was winding down, Lincoln knew that these Confederate States would eventual become part of the US again. To ease this transition, he discusses how the US must "bind up the nation's wounds." When using this phrase, Lincoln is referring to how the Confederate and Union states must work together in order to unite the US once again.
Africa’s physical geography, environment and resources, and human geography can be considered separately. The origin of the name “Africa” is greatly disputed by scholars. Most believe it stems from words used by the Phoenicians, Greeks, and Romans.