Answer:
C
Explanation:
A has two commas too many (but, flounder, is) because there is no pause after but and flounder.
B has one comma too many (dirty, on the job) for the same reason as A
D can do without a comma (or, voters) because or is a conjunction that is mend to join words.
So therefore it must be C where the comma is used before the contrasting second part of the sentence, introduced by yet another conjunction.
