During the enlightenment period the phiolopshers questioned what group ?

Either the monarchy or Catholics

Correct answer is They were centers of trade.

Explanation:

First option is not correct as until Hammurabi's Code (Old Babylonian Empire) there were no written laws in this area.

Second option is correct as all of this cities were large and important crossroads of trade, due to their position.

Third option is not correct as they all had different rulers.

Last option is also not correct as together all of them had less than a million inhabitants.