Answer:
D. Many tribes, like the Chickasaw, created their own drilling companies to exploit the vast wealth of their oil fields
Step-by-step explanation:
As it turned out, the land they had chosen was rich in oil, and in the early 20th century, members of the tribe became spectacularly wealthy. They bought cars and built mansions; they made so much oil money that the government began appointing white guardians to "help" them spend it. And then Osage members started turning up dead.