Answer:
The correct answer is C. The most significant result of General Grant's victory at the Battle of Vicksburg and the capture of Port Hudson was that it gave the Union control of the Mississippi River.
Step-by-step explanation:
The Siege of Vicksburg, that ended the Vicksburg Campaign, was a major turnign point of the Civil War as it allowed the Union to take control of the Mississippi River in its both ends, thus cutting the Confederacy into two halves. As a consequence, both halves of the Confederation were isolated from each other, so the transference of resources and military supplies was impossible. This led directly to the final defeat of the South in the war.