The question wants the gist of Linda's response to Bruce's claim that regardless of the sacrifices entailed, country X should give back the province it annexed a century ago, on the grounds that the annexation was "unjust." Linda replies, in essence, "unjust, my foot." To her, the unjustness of the original act is beside the point; what matters is whether the return of the province will benefit country X's own citizens. (A), therefore, has it just right, Linda already having defined the enhancement of a country's well-being as that country's "paramount responsibility." She sees that well-being as a necessary condition of any act-such as the return of the province-that would require sacrifice.
Choices (C) and (E) go astray on the same issue-namely, the amount of sacrifice required. Linda never implies that there is no sacrifice too great for a nation to make (C), nor does she establish minimal sacrifice as a precondition (E). Her only concern is in first establishing the tangible benefit of a course of action before taking that action. Both choices have other problems, of course: (C)'s reference to "future well-being" is too far removed from the concept of "tangible benefit." And (E)-like (B), for that matter-errs in that Linda has no interest in righting historical wrongs; that's Bruce's department.
(D) Linda makes no appeal to consensus as a precondition for returning the province. We can't be sure how Linda thinks the "tangible benefit" would be determined, whether through a poll of the citizenry or by some other means.
