The correct answer is C) keep the Union intact.
To many people, especially in the North, they would be fighting the war to keep the Union intact.
The Northern States and the Southern States were increasing their differences on a daily basis. The Civil War was imminent. The Confederated States heavily supported slavery. Indeed, they depended on slavery to export their crops. That is why landowners had slaves in their southern plantations. People in the North supported abolitionist and the confrontation and differences were irreconcilable.