Why is B incorrect?

@Shiyi-Zhang, Happy to help. The stimulus tells us that government administrators have taken positions in private-sector management because of the disparity in pay between private and public organizations. The stimulus then tells us that if this gap is closed, the government administrators will go back to their government jobs. The argument concludes that as a result, public agencies will have better functioning. But wait. The argument is relying on a major surge of the government administrators returning back to the public sector will improve the public agencies' functioning. The question stem asks, "The position taken above presupposes which one of the following?" In other words, we're looking for a necessary assumption that this argument depends on. In identifying the correct answer choice, we can use the negation test on the different answers to determine which answer is essential in order for the argument not to be wrecked. You asked about (B). In using the negation test for (B), we have the most important factor determining how well government agencies function is not necessarily the amount of experience the administrators have. If this were true, does it wreck the argument? Not, it does not because the argument doesn't suggest that the amount of experience the government administrators have is the most important factor in determining how well government agencies function. Instead, the argument suggests that the return of government administrators from private-sector positions will lead to the better functioning of public agencies. If the negation of (B) were true, the argument would not be wrecked, so we know that (B) is not a presupposition of the argument. (D), on the other hand, is the correct answer. (D)'s negation is that people who moved from jobs in government administration to private-sector management would not necessarily choose to change careers again. If (D)'s negation were true, the argument would be wrecked because if people who switched from the government jobs to the private sector aren't switching back, then there's no way that the government would be able to recapture these capable administrators, which casts doubt on the conclusion that the functioning of public agencies will be improved. Since (D)'s negation wrecks the argument, we know that (D) is essential in order for the argument to stand a chance, so it's the correct answer choice. Does this make sense? Let us know if you have any other questions!

Does this mean that being an administrator/manager in public vs. private organizations would be "changing careers"? That is tricky because I didn't see it that way. If they were going from administration to sales, that would be "changing their career". A good administrator can administrate and manage anywhere.

Hi @Audrey, I think generally, we should presume that this kind of changing is a "career change." Two other factors to consider: one is that none of the other answers are necessary, and this interpretation of this answer choice makes it necessary, so we should go with it. Another important factor is that the answer choice reads "change careers AGAIN," which implies that the first "career change" fro public vs. private is counted as a career change. Hope this helps!