My answer is
(A). The deliberation between (A) and (C) took most of my time.
(A) sounds good. "either ... or... " is parallel. Keep for now.
(B) Not a sentence: after "although .... bureaucracy", there is no subject for the main clause.
(C) While it does not sound as well as (A), we have to be careful not to be biased by our familiarity with previous options. Keep for now.
(D) "most of Kafka’s books and also" is not grammatically correct. I wonder if this is a typo.
(E) Originally, I eliminated by its use of "and". Now, I think "and" is not necessarily fatal. (The elimination based on "and" is an example of bias caused by previous options.)
"and" is fine, and "but" may be a bit extreme.
Now, there are two considerations stacked against (E).
(1) "within these books, there is also" is rather wordy. "these books also" suffices. Do not overuse "there be".
(2) See the ensuing discussion about option (C)'s use of "a protagonist's loss of identity under a tyrannical regime or disenfranchisement by an oppressive bureaucracy".
We have to find a winner between (A) and (C).
I feel that (A) reads better than (C). I can ascribe such feelings to two factors now.
(1) (C) uses "but", which is a bit extreme. (Note that (A)'s use of "although" does not sound abrupt at all.)
(2) (C) uses "there be"
Still, feelings are not always reliable (but should be relied upon as the last resort).
The most important criterion is meaning!
Yet, it is hard to determine what the right meaning is! That is why it is time consuming.
In (A), its meaning is clear:
most of Kafka’s books are centered on
either a protagonist's loss of identity under a tyrannical regime
OR
disenfranchisement by an oppressive bureaucracy
But is it the right meaning? Maybe the correct meaning is
most of Kafka’s books are centered on a protagonist's loss of identity
under
either a tyrannical regime
OR
disenfranchisement by an oppressive bureaucracy
In (C), it can actually mean
Most of Kafka’s books are centered on
a protagonist's loss of identity
under
a tyrannical regime
OR
disenfranchisement by an oppressive bureaucracy
But it can also be interpreted as
Most of Kafka’s books are centered on
a protagonist's loss of identity under a tyrannical regime
OR
disenfranchisement by an oppressive bureaucracy
Ultimately, I rejected (C) and chose (A) because (C) lends itself to two different interpretations. By using "either...or...", (A) removes ambiguity. (Still, if the meaning of (A) is nonsensical, we should choose (C) despite its defects. Meaning is of supreme import. I, however, am at a loss as to its meaning.)