I am not very much sure for my answer but I choose
A option.
1) Idiom tested-
Not only X but also Y and
Not only X, Also Y; now, both are correct on GMAT. I eliminate c,d and e option because i was not able to find the subject. Intended meaning - Culprits can also discard mine waste, but in c,d and e; the subject is not given, Who discard mine wastes ?
2) In between A and B, i choose A because '
such as' is mostly used for the list of items.
Moreover in B, Discard and Facing is not parallel
A. they can also discard mine waste such as the sludge and slurry leftover from copper, dredged material, toxic waste, and face-
CorrectB. they can also
discard mine waste that includes the sludge and slurry leftover from copper, dredged material, toxic waste, and
facingC.
also discarding mine waste including the sludge and slurry leftover from copper, dredged material, toxic waste, facing
D.
but also discard mine waste such as the sludge and slurry leftover from copper, dredged material, toxic waste, to face
E.
but also discarding mine waste such as the sludge and slurry leftover from copper, dredged material, toxic waste, and facing