The correct answer is A) it meant that Union troops controlled the Mississippi river ports.
The capture of Vicksburg, Mississippi, by Union troops, was significant in that it meant that Union troops controlled the Mississippi river ports.
The Battle was fought from May 18 to July 4, 1863. Union General Ulysses S. Grant pressed the troops of Confederate General John Pemberton, and finally, Pemberton surrendered on the 4th of July. Vicksburg had been captured by the Union Army. Now the Union controlled the Mississippi River and the Confederate States were split by it. This victory was so important for the Union and for Grant, that after it, Gran became the General-in-Chief of the Union troops.