Answer: B. because of how their governments were organized
Step-by-step explanation:
The Cherokee, Chickasaw, Creek, Choctaw and Seminole tribes were considered to be "civilized" because they seemed to be adopting European ways of doing things such as centralized governments, marrying white people, adopting literacy and Christianity and animal farming.
With Governance, they instituted reforms that led to a more united and centralized Government with the Cherokee for instance establishing a National Supreme Court and a written constituition.