A, B, C are incorrect as workers are compared with package - comparison must be between "most severance packages" and "the automobile company's severance package."
E is incorrect as it changes the meaning - "last day that they are scheduled to collect" creates confusion. "To collect" is misplaced. E says "the last day that they are scheduled to collect," suggesting illogically that workers can be scheduled to collect a day.
D is the best choice. Right usage of "Unlike"; it is concise.
