What implicit warning is contained in Senator Gravel’s introduction?

The true strength of rulers and empires lies not in armies or emotions, but in the belief of men that they are inflexibly open and truthful and legal. As soon as a government departs from that standard, it ceases to be anything more than “the gang in possession,” and its days are numbered

Explanation:

he uses H.G. Wells words to explain when a goverment lies to its people it is nearing an end. http://www.archipelago.org/vol10-12/gravel.htm

the answer is b: the religion they practice.

here's why:

there were many different native american tribes and those with similar characteristics formed a main tribe or nation. each had its own language, religion and customs.