This is a comparison question.
The structure is:
unlike X, Y.... <== X and Y should be parallel in terms of meaning.Unlike exploring wrecks for recreational divers, in government concerns they are analyzed over a period of years in order to identify environmental dangers and protect military secrets.
(A) Unlike
exploring wrecks for recreational divers, in government concerns
they are analyzed
Wrong. "they" refers to "exploring wrecks"? That makes no sense.
(B) Unlike wrecks that are explored by recreational divers, in exploring for government concerns, they are analyzed
Wrong. Incorrect usage of structure "unlike X, Y...".
Like/Unlike never + Clause.Like/Unlike + noun/noun phrase ONLY.
(C) Unlike
recreational divers exploring wrecks,
analyzing wrecks in government concerns is done
Wrong. Incorrect comparison: recreational divers VS. analyzing wrecks? That makes no sense.
(D) For recreational divers, wrecks are explored briefly, whereas for government concerns wrecks are analyzed
Correct. Good structure:
for X, wrecks are explored briefly, whereas for X wrecks are analyzed.....(E) For recreational divers,
the exploration of wrecks is brief, whereas for government concerns
they are analyzed
Wrong. Incorrect comparison. "they" refers to "the exploration" <== Totally wrong.
Hope it helps.