PLEASE HELP 40 POINT PLEASE 40 POINTS ASAP
One of the major failures of Reconstruction efforts was that:

A.
maintaining martial law in the South greatly weakened the U.S. military.

B.
the Freedmen's Bureau was taken over by Southern plantation owners.

C.
African Americans lost their civil rights when federal troops left the South.

D.
Congress refused to admit African Americans elected to represent the South.