Answer:
The main goal has always been
d. reunite the country.
Step-by-step explanation:
In America, the issue of slavery was such a strong topic that most american president tried to overlook abolishing it or looking into it or using the topic to campaign during election time. When Lincoln became president, he promised to abolish slavery which didn't go down well with those living in the Southern States in America.
This issue caused them to try to form and declare their own country. America being a single indivisible country tried everything possible to prevent such. When it didn't work, the Northern States had no other option than to go to war with the Southern States inorder to preserve their sovereignty as a single country.