What does the reference to the United States' centennial help the reader understand about the creation of Yellowstone, National Park?

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

the right answer for the question that is being asked and shown above is that: "their policy of "divide and rule" pitted political groups against each other to keep any one group from becoming too powerful.  " the  participant in european imperialism is being described below is that  their policy of "divide and rule" pitted political groups against each other to keep any one group from becoming too powerful. 

it made them more prductive and efficent but with the change of polcies less and les got into the navy