The correct answer to this open question is the following.
Although there are no options attached we can say the following.
The legal tactic was used by whites in the post-Reconstruction South to deny blacks their voting rights was "poll tax."
During the Reconstruction years after teh American Civil War, southern whites refused to give formerly African Americans slaves their full rights.
Southerners created a series of laws and legislations such as Jim Crow laws and the black codes to limit the black's rights.
Among those decisions to limit black people's rights, the Poll Tax limit Blacks the right to vote. Knowing that blacks were poor people, whites knew that implementing a poll tax would dissuade African Americans to vote. So the Poll Tax was a requirement to vote. It was created to exclude black people.