What best states the main reason for the Unions success in the West during the Civil War?

The main reason for the Union's success in the West during the Civil War was its superior resources and infrastructure, which allowed for better supply lines and troop movements. Additionally, effective leadership, particularly by generals like Ulysses S. Grant, and coordinated strategies contributed to significant victories, such as the capture of key locations like Vicksburg. The Union's ability to mobilize and sustain large armies in the region ultimately led to the weakening of Confederate forces and control over the Mississippi River.