Sorry for the delay; this post fell through the cracks.
When RC questions ask
===
the author mentions ____
in order tothe author brought _____
primarily tothe author's reference to _____
serves to===
the correct answer is usually just reinforcing the broader idea that came BEFORE the sentence with the ____ or AFTER it.
Essentially, these questions are testing WHY the author brought up a
specific detail/example, so they want the
broader point that is being illustrated by the specific.
Here, the broad idea before this Council of Basel sentence says "Second, church authorities themselves complained about canon lawyers' ethics".
Hmmm, "Second"? What was "First"? That traces back to line 31. Collectively, these two ideas are fleshing out line 30-31, that canon lawyers DID deviate from standards of ethics but escaped punishment.
(A) it was an example of how church authorities were expressing concern about canon lawyers' ethics
(B) no contrast - in fact, the sentence about English authorities uses "similarly"
© This works, since line 47 is support for lines 44-47, which is the 2nd prong of the author's 2-pronged argument that "the second explanation is more plausible".
(D) The Council of Basel didn't establish rules of conduct.
(E) Did the Council of Basel develop a disciplinary system? It asked a Cardinal to address the problem, but we don't know if the Cardinal developed a disciplinary system.
I see where you were going with you're thinking for (E), but you're trying to connect the Council of Basel forward in the passage. The sentence being tested begins with THUS, which means it's connected to the previous sentence. The previous sentence begins with SECOND, which means it's connected to a two-part idea. The two part idea is line 30-31, and © is just paraphrasing that.
Confusing enough?