According to the professor’s philosophy, the antidote to envy is one’s own work, always one’s own work: not thinking about it, not assessing it, but simply doing it. (A) one’s own work, always one’s own work: not thinking about it, not assessing it, but simply doing it (B) always work; because you d...

IMO: C
As should be used when the sentence compares actions

A, B tense mistake when 2001 has stated.
D,E which is redundancy

C is right one.

in option A,
That refers to what is exact particles.
if there is no first "that" the second "that" cannot be alive.

C cannot be correct because which is vague.

IMO: E

i am really difficult to understand C is the OA.

E is more clear than others.

A,B, D drugstores - plural should be eliminated because of pronoun its.

based on the passage.
B is prefer to A,
antique is a adjective, it modify for things (n)
the subject here is fascination, not things,
it explains why has is used here .

IMO: D
the underline part functions as adjective phrase modifying for the subject.