Answer:
Correct answer is Each Sumerian city was independent from the others.
Step-by-step explanation:
First option is not correct as priests were not leading army, but were serving in the temples called ziggurats.
Second option is not correct because the mentioned ziggurats were the central building.
Third is correct because there were many city-states such as Uruk, Ur, Lagash and many others that had political independence.
Fourth is not correct as the ruling class was consisted out of rulers and the people who surrounded them.