Respuesta :
By gaining the control over the Mississippi River at the time of the Civil War, the North states will be allowed to keep the support of the border states.
What happened during the Civil War?
During the Civil War, the North American states gained a control over the Mississippi River and the neighboring region. This in turn, gave them access to the support of the border states.
Hence, option A holds true regarding the events during the Civil War.
Learn more about Civil War here:
https://brainly.com/question/11874600
#SPJ2