The sources of powers reserved to the states are specifically outlined in

The sources of powers reserved to the states are specifically outlined in  the Tenth Amendment.

The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people. The Tenth Amendment was included in the Bill of Rights to further define the balance of power between the federal government and the states.

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explanation:

c. troops marched forward in close formation against newer, more accurate weapons