B. They allowed groups such as the Ku Klux Klan to terrorize blacks.
The Ku Klux Klan (or KKK) was a secret organization of white men (typically) that masked themselves and terrorized blacks. They burned down black towns, murdered and lynched blacks, and raped black women.
The government didn't try to stop them.
Hope that helped!
This is the treaty in which Spain seceded Florida to the
U.S. It also gave the natives in the area a required area to live in.