According to some historians, which marks the beginning of the us civil war

Bloody Kansas and Election of President Lincoln

Explanation:

The South belived that Lincoln was going to free all the slaves until states from the south started to succeeded from the union. Bloody Kansas caused people from the north and south to compete for the right of free or non free slave state.

"a government in which power is divided between state and national levels". federalism is a system of government in which entities such and state and province, share power with the national government.

the answer is a, salt plain