Explanation

An initial reading of this sentence might suggest that the blank should be filled with a word like “complex” that indicates how hard it is to “make sense of” the digressions. However, there is no such word among the answer choices. Focusing on the second half of the sentence suggests a different interpretation. According to the sentence, it would be “wise to” make sense of the digressions, and a textbook would help the reader to do so. If the digressions are “uninteresting,” “unsophisticated,” or “humorless,” the sentence provides no reason to think it would be wise to make sense of them, and if they are “controversial,” it provides no reason to think that a textbook would help. Only if the digressions are “frustrating” does the sentence make a coherent whole.
Thus, the correct answer is frustrating (Choice D).
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Sandy
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https://www.youtube.com/watch?v=6yw9hp6 ... b9vQvgxnli

Here, our Dear Brent helps the students that face your same problem.

Soon, I will do a tutorial on how to tackle (i),(ii),(iii) blank questions.

Regards
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Have you managed the time to make the video? Would have been handy for me. If you already did, please share the link.

Regards,
Scrat

Unfortunately Sandy is no longer part of the team.

The most important thing is to really get an understanding of the sentence and its real meaning


The unexplained digressions into the finer points of quantum electrodynamics


The digressions are a departure from the main subject of the discussion. However, even you do not get this point is not a problem after all. The only thing you should understand is that the quantum (we are talking about physics)...something


are so (i) ________



that even readers with a physics degree would be wise to keep a textbook handy to make sense of them.


This is tyhe most important part of the entire sentence, which basically is saying that even the most skilled scholars must have in handy a book to keep track of important concepts.

Turns out, the blanks

A uninteresting

out of scope. we need a word that says us that the scholars need help because the matter if difficult to disentangle.

B controversial

No . it is wrong because we are not talking of controversial issue sor debates

C unsophisticated

Out of scope. Quantum is so complex that is the contrary: the matter is sophisticated

D frustrating

The right fit. They are frustrated because even though they are really skilled (think about professors) they need a book in hand to get fully certain concepts

E humorless


Not on point. Out of scope.
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