The American Civil War broke out mainly because______.

The American Civil War broke out mainly because______.
A、Abraham Lincoln was elected president
B、Harriet Beecher Stowe’s Uncle Tom s Cabin was published
C、the southern states controlled land，raw materials and labor that the North needed
D、the southern states broke away from the Union and formed the Confederate States of America
【正确答案】：D
【题目解析】：南部诸州退出了联邦，成立了一个新的国家—“美利坚联盟”，林肯决定维护联邦统一，内战爆发。