Which factor is unique to the city-states of Mesopotamian civilizations? A. location along the Tigris and Euphrates rivers B. dry, arid weather C. evidence of monumental architecture D. remains of a settlement

Here is the right answer to your problem  (A.)

they had many gains 1 one freedom for slaves the major cause of the civil war is that the   north wanted freedom for slaves but the south didn; t creaitng the civil war

another gain they have is poltiical influence

poltiical influence is a big thing everywhere even now peoplle are always trying to get the head up in poltics thats what they did by giving the republicians a good name for freeing slaves