Which of the following contributed to the increased economic and military power of the sumerians?

The Euphrates and Tigris rivers contributed significantly towards crop growing which in turn protected the natural resources.

Each city of the Summerland had their rulers. The leaders were identified by their different titles, and the rule was more like a governor. He was also considered as the high priest of the religion, and this, therefore, gave him the power of becoming a famous king in Uruk. Further, there were sophisticated government rulers who helped in organizing the project in the city to ensure the city was running.

the answer is:

c. economic output

this is not a question