Unlike most severance packages, which require workers to stay until the …

Correct answer is (D).

Answer choices (A), (B), and (C) contain an easy-to-spot comparison error that you should see quickly and confidently: “Unlike most severance packages, garbage modifier you should remove, workers/automobile company”. Since you cannot compare severance packages to either workers or an automobile company, these answers should be immediately eliminated. The question writers attempt to hide this comparison error by using a “which” clause between the two elements being compared, but that con is easily overcome by simply removing the modifying clause and checking the comparison without it.

The choice between (D) and (E) is hard—it is exactly the type subtle meaning issue that is used on most high-level sentence correction questions. People get pretty good at spotting concrete grammar errors (like the comparison error in (A), (B), and (C)), but they are not so good at spotting issues relating to illogical meaning. The only difference between (D) and (E) is this portion: 

– which requires workers to stay until (D) their last scheduled day in order to collect
– which requires workers to stay until (E) the last day that they are scheduled to collect

To get this correct, you must carefully analyze that change in wording and figure out what makes one logical and one illogical. In correct answer (D), the workers must stay until their last scheduled day (their last day of work) in order to collect the severance. Makes perfect sense and conveys the meaning properly and logically.

However, in (E), the workers have to stay until the last day that they are scheduled to collect. Wait: this means that there are multiple days scheduled by the company for the workers to collect their severance, but they must stay until the last of those days to collect. That is completely illogical—why would there be multiple scheduled days for collecting severance if you only get it by waiting until the last day?!?! (E) subtly modifies the “last day” improperly: it is saying the last day in which they are scheduled to collect, when it is supposed to be their last “work” day. Only (D) does this properly. 

The only way you will get this type of question correct is if you carefully analyze the changes between the two answers and figure out what makes one incorrect—either because of a grammar issue or because of an issue of illogical meaning. If you simply go back and forth between these two choices and pick the one you think sounds better, you would be better off flipping a coin! You can figure out why (E) is wrong, but only if you are highly analytical and learn how to spot well-hidden errors of illogical meaning. You will simply not find this type of hard, subtle meaning error through unofficial GMAT sentence correction practice, and thus you will not be ready on test day unless you prepare with official questions.