What impact did they have on Americans living in the Great Plains

Human impact on the enviorment was limited by enviromental constraints.

Explanation:

in 1897, pershing became a tactical officer at west point, and that's where he was given the nickname "black jack." pershing's first name is "john," for which "jack" is a nickname, and he was a white man who commanded black troops. hence "black jack".

c would be the correct !

hope this !

~bbgluver