To fill in the cause and effect, we can organize the responses as follows:
Cause:
- a standing army of many trained soldiers
- the formation of alliances with other city-states
- a series of highly strategic army leaders
- the development of bronze to make weapons
Effect:
increased economic and military power
So, the correct arrangement would be:
- a standing army of many trained soldiers → increased economic and military power
- the formation of alliances with other city-states → increased economic and military power
- a series of highly strategic army leaders → increased economic and military power
- the development of bronze to make weapons → increased economic and military power
All responses contribute to the increased economic and military power of the Sumerians.