OE

This sentence begins with the expression “For all,” an idiomatic way of saying “despite.” The second half of the sentence, then, should contradict the “meticulous preparation” reported in the first half: the student’s grade must have been bad. “Passable” wouldn’t do the job here—it would suggest a decent but not fantastic grade—and “outstanding” is the exact opposite of what you want. “Exacting” means demanding, and while the test must have been exacting on the student, his grade could not be described as such. “Surprising” is the most pernicious option, because the student was likely very surprised by a grade that did not reflect the work he put into studying; this choice does not make clear, however, that the student’s grade was terrible. “Deplorable,” on the other hand, fits the bill—it means surprisingly bad.