Final answer:
The Battle of Gettysburg is a turning point due to it being the last Confederate invasion into the North, resulting in significant Confederate losses and marking a shift in the war's momentum toward the Union.
Step-by-step explanation:
The Battle of Gettysburg is considered a turning point in the Civil War mainly because of option A: It made the South give up the idea of invading the North. During the three-day battle that began on July 1, 1863, the Union Army dealt a significant blow to the Confederate forces under General Robert E. Lee. The Union's defense at Culp's Hill and the failure of Pickett's Charge led to devastating Confederate losses with around 28,000 casualties. This defeat, coupled with the Union's victory at Vicksburg, which gained them control of the Mississippi River, marked a shift in momentum towards the Union cause. The Confederate's loss of momentum and their inability to maintain their invasion of the North showed a decisive change in the war's direction, making the Battle of Gettysburg one of the most critical engagements of the Civil War.