This is a Strengthen question, and we're trying to strengthen the argument of the person who wrote this letter based on new information presented in the answer choices. She's arguing that even though the budget increased, it's not true that the department spends five times as much money to perform the same duties. Since the figures at least match up, a natural thought would be that perhaps the duties of the department have changed, and this is what (E) tells us. The "same duties" part is what makes (E) the correct answer.
(D) is incorrect because even if the numbers were adjusted for inflation in the original editorial, the ratio between the two would stay the same, since the numbers from both years would either be adjusted or unadjusted. Hope this helps!