The correct answer is A) the Union.
The side that conducted a successful blockade during the Civil War was the Union.
The Union blockade during the Civil War was a successful decision by the Union Army in that it caused inflation and shortages in the South, such as manufactured goods. The union blocked Confederation Ports to prevent the export of Cotton and the import of war supplies that could benefit the Confederated Army. The blockade was successful, but the Confederates found ways to smuggle cotton and weapons through other parts like Mexico.