Mechanisms for employee participation in corporate decision

Mechanisms for employee participation in corporate decision making that are merely advisory obviously fall short of
meeting the ethical standards of fairness; the weaknesses of individual contract negotiations are less obvious
than these participatory mechanisms, as is union membership, and stock ownership as devices for
guaranteeing fairness.

A. the weaknesses of individual contract negotiations are less obvious than these participatory mechanisms, as is
B. the weaknesses of individual contract negotiations are less obvious than these, as are those of
C. less obvious are the weaknesses of individual contract negotiations,
D. less obviously, the weaknesses of individual contract negotiations are
E. individual contract negotiations have certain less obvious weaknesses, as has

Before moving any further, first note the ";" separating the two clauses together. Hence the two clauses must be related to each other and must be independent.
The logic of the sentence in first clause is "Mechanisms for employee participation are not comletely fair". In the next clause, we must have to say something that relates to this, is a complete clause, is concise and is logically correct.
If you wanna attack B, then you have a good reason to point to just "these". On GMAT just "these" is incorrect and moreover it does'nt relates to the previous clause IMO.
In A, the comparison is being made between "weaknesses" and "participatory mechanisms".
In D, "less obviously, the weaknesses of individual contract negotiations are union membership, and stock ownership as devices for
guaranteeing fairness" The cant really understand the logic of this red part. What does the sentence means by saying ",and stock ownership as devices for guaranteeing fairness". Moreover, the context in which "stock ownership" and "union membership" are written, are not parallel.
In E, the same error. The context in which "stock ownership" and "union membership" are written, are not parallel.
Among the above options, C makes the complete sense.
+1C
IMO.
Hope that helps.
-s