Answer:
The letter C is the right answer.
Step-by-step explanation:
In 1862, Grant had repeatedly attempted to capture Vicksburg, the last confederate key city that was missing to be captured by the Northerners on the Mississippi River. This attempt began with attacks in the northern sector of the city, which resulted in failure, thanks to the geographical conditions of the region. In April 1863, Grant decided to change his strategy, and on the night of May 18, Grant and some of his forces moved south through the Navy. When the Confederates found out, it was too late, and the Northerners completely surrounded the city, which surrendered on July 4. The Mississippi River was totally in Northern hands.