What made nightriders $($like the Klan$)$ so hard to catch & punish?

Select one:

$9$a$.$ The law did not give the Freedmen's Bureau or Army the authority to deal with them

O b$.$ The Klan were careful to hide their identities and strike far away from help

c$.$ Despite local authorities attempting to help, they likewise did not know who Klan members were

d$.$ None of the above