I agree absolutely with SDGraham. The answer is "fussy".
I disagree with the general concensus that the test writer's methods are questionable. In my mind, these questions prompt the student to think about the entire sentence rather than just the individual, fill-in-the-blank word. As SDG said, the use of "insisting" is the clue to the answer but unless you absorb and comprehend all of the words, it's easy to get side-tracked.
I also think it's "fussy." Someone can be quite particular about things being in a certain place without being fastidious at all. A place can be quite a mess and still be a mess with a very particular organization to it. I speak from experience.