Final answer:
A disruption of the Federal Union refers to secession, or the breaking away of southern states from the Union. The southern states believed that they had the right to withdraw from the Union and form their own government.
Step-by-step explanation:
In this context, a disruption of the Federal Union refers to B. secession, or the breaking away of southern states from the Union. The southern states believed that they had the right to withdraw from the Union and form their own government, separate from the federal government. This ultimately led to the formation of the Confederate States of America and the American Civil War.