Question

How did some southern whites deny justice to blacks during Reconstruction?

Answer 1

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!