The COVID-19 pandemic has led to significant organizational changes in

Ron's explanation:

Two main structural elements of this sentence are written in differing ways among the answer choices: the modifier at the beginning of the underline, and the parallel comparison structure signaled by MORE ____ THAN ____ at the end of it.

The modifier must correctly answer this question: “WHAT, exactly, did analysts view more as X than as Y?”
This sentence is about certain analysts’ view of the organizational changes catalyzed by the COVID-19 pandemic in certain parts of the American economy. This isn’t the nearest noun (or even the second-nearest noun + modifier!) to the comma, so we can’t use a WHICH modifier here.
A generally descriptive noun phrase as a modifier (an ‘appositive’), on the other hand, is allotted greater flexibility to describe a more distant noun + longer modifiers—as long as this meaning is clear in context. In this case, a restructuring… can be used to describe significant organizational changes in certain segments of the U.S. economy.

The parallel parts of the comparison that ends the underline can be analyzed mechanically: the two ‘blanks’ in MORE ____ THAN ____ need to contain properly parallel elements.

A/
The WHICH modifier is inappropriate here, since that modifier is not meant to describe the nearest noun (or the next-nearest noun + short modifier).
Additionally, MORE is followed by as a permanent restructuring (a modifier) whereas THAN is followed by they see it as a temporary response… (an entire clause with a subject and a verb). These parts are not parallel.

B/ CORRECT ANSWER
As explained above, the appositive modifier a restructuring... is properly used to describe significant organizational changes in certain segments of the U.S. economy.
MORE is followed by as a permanent change; THAN is followed by as a temporary response… These are perfectly parallel modifiers of the same kind.

C/
The type of modifier used here isn’t necessarily problematic, but the timeframe implied by having seen is illogical: Having VERBed describes an action taken or completed PRIOR TO the timeframe of the clause to which it’s attached. Clearly it’s not possible for analysts to have already formed opinions on these changes before they even happened!
(The parallel comparison is OK here. MORE is followed by as a permanent restructuring; THAN is followed by as a temporary response… These are parallel modifiers of the same kind.)

D/
The appositive modifier a restructuring... is properly used to describe significant organizational changes in certain segments of the U.S. economy.
The following comparison, however, is nowhere close to parallel. After MORE we have by some analysts as permanent; after THAN we have a temporary response… The inclusion of by some analysts in the first part ruins the parallelism already—and, furthermore, as permanent (a modifier) is not parallel to a temporary response… (a noun phrase).

E/
The WHICH modifier is inappropriate here, since that modifier is not meant to describe the nearest noun (or the next-nearest noun + short modifier).
(More of [a/an] X than [a/an] Y, in which X and Y are nouns or noun phrases, is an acceptable idiomatic structure here.)