Official Answer : Read the sentence, looking for clues

The phrase "in order to" suggests that the sentence presents a problem and a solution. The problem is that people think the "unscrupulous" divers are wrong to remove the artifacts. The solution that will justify removal of the artifacts is for the divers to appear to care about preservation and research rather than themselves.

Predict an answer

Since the divers want to avoid appearing selfish and unjustified, the correct answer will mean something similar to "unselfish," or acting for an legitimate and just purpose.

Select the two choices that most closely match your prediction

(A) altruistic and (E) selfless are both synonyms of "unselfish" and fit the prediction well. These are the correct answers.

Adopting an omnipotent (B), meaning all-powerful, attitude would not help the divers appear unselfish. Nor would adopting an insular (C), or narrow-minded, attitude.

Attempting to appear arrogant, or overconfident, is unlikely to help the divers justify their actions. Thus, (D) arrogant can be eliminated. (F) perfunctory, which means "indifferent" or "routine," can be eliminated because appearing indifferent would also not help the divers justify removing artifacts from shipwrecks.

Check your answers to see if the sentence retains the same meaning

In order to justify their removal of historic artifacts from shipwrecks, unscrupulous divers often adopt a seemingly altruistic/selfless attitude, aligning themselves with the preservationists and professing their devotion to education and research.

TAKEAWAY: The correct answer choices not only have to yield complete sentences that are similar in meaning, but also have to fit the meaning of the sentence as a whole.