Of all the metaphysical theories that attempt to reason human existence, Kierkegaard's existentialism is maybe the more difficult for analysis.
A) is maybe the more difficult for analysis
is the more difficult for analysis; compared to whom. In this sentence superlative form of the adjective 'difficult ',most difficult and not comparative form 'more difficult' is required.
B )is probably the most difficult for analysis
'difficult for analysis' does not sound good and the answer choice is passive
C )is maybe the most difficult to analyze
not the best answer choice but the best out of the lot
'difficult to analyze' is better than 'difficult for analysis'.
D )is probably the more difficult for analysis
same problem as A
E) is, it may be, the analysis that is most difficult
the sentence formation is awkward