Your Answer would be D, Hope This Helps
Actually every single one is correct, A<B<C they all are factors in the decline of Sumer.
The history of Kansas, argued historian Carl L. Becker a century ago, reflects American ideals. He wrote: ... When the area was opened to settlement by the Kansas–Nebraska Act of 1854 it became a battlefield that helped cause the American Civil War. Settlers from North and South came in order to vote slavery down or up.
HOPE IT HELPS YOU
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