In Mesopotamia, each city was largely cut off from its neighbors as A
There were often floods in summer.
B
The harsh landscape made it hard to travel by land and communicate with other groups.
C
City-states traded with each other.
D
From time to time they formed alliances to protect their common interests.

It is B the landscape made it hard to travel by land and communicate with other groups.

it took two men to wrestle rome back from chaos and turn a republic into an empire. in the first century bc, rome was a republic. power lay in the hands of the senate, elected by roman citizens. but the senators were fighting for power between themselves.