The correct answer is - trade.
The Sumerians engaged in trade with their move of exchanging their surplus food for materials like the copper that they needed to develop their weapons and thus their army forces. This was a very smart move from their side because they managed to use the resource they had in abundance but was scarce in the other surrounding areas so that they take what they need to become stronger and pretty much defend more efficiently from the same people they were engaging in trade with.
"b. They opposed them by <span>charging that they were unconstitutional" is the best option since this group considered the acts to be a serious violation of their rights as citizens, even in times of war.</span>
