The correct answer is C) The Southern blockade was working.
According to the lesson, one reason why Lee decided to invade the North was that the Southern blockade was working.
In June 1863, General Robert E. Lee of the Confederate Army led the Northern Virginia troops to invade the North and had a great victory when they defeated the Union Army of the Potomac. But what happened next was the Battle of Gettysburg from July 1 to the 3rd, a bloody battle that was won by the Union Army and historians considered a turning point in the Civil War.