One thing that I noticed is that all of these answer choices start with the phrase, "Although some argue that the authority of legal systems is purely __________...". From the passage, we know that some critics believe one way (institutional) and a judge believed the other way (intellectual). Therefore, I don't think it really matters how the answer choice starts, both are definitely supported.
- (A) "These legal systems possess a degree of institutional authority..." This phrase is certainly supported by the author. However, I am a little bit suspicious already because the author was mainly hinting at (in the final sentence of the passage) that the courts were "predominantly institutional" with a "significant degree of" intellectual. Thus, though this answer choice's beginning is certainly supported - it is a bit lacking in nuance.
"due to their ability to enforce acceptance of badly reasoned...decisions." This doesn't capture the author's point at all. There are a few reasons why the author believes that the court system is institutional - precedent being the main reason - however I don't think there's any support for being institutional because of their ability to enforce.
(B) Possessing "no coercive power" grossly misrepresents the author's point. We know the author believes that the courts are "predominantly institutional."
(C) "Intellectual authority reduces to institutional authority." Some critics do in fact believe this, as we see in line 18. However, the author doesn't really seem to make this out to be the main point of the passage. The author doesn't merely state that all intellectual authority that the court possesses just becomes institutional. The author separates these concepts and says that the courts contain both (though one more than the other).
(D) Bingo! Perfect match for the final paragraph - the author's main point.
(E) This is like (B), "exclusively institutional authority" is not supported.
From this question, we can see that the money sentence is the final one. The wrong answers seem to misrepresent it while the right answer basically restates it.
In addition, we have to make sure to keep the critics views separated from the author's views! We could have fallen trap to wrong answers by merely word matching!