单选题 6.For over two centuries, no one had been able to make Damascus blades—blades with a distinctive serpentine surface pattern—but a contemporary sword maker may just have rediscovered how. Using iron with trace impurities that precisely matched those present in the iron used in historic Damascus blades, this contemporary sword maker seems to have finally hit on an intricate process by which he can produce a blade indistinguishable from a true Damascus blade.
Which of the following, if true, provides the strongest support for the hypothesis that trace impurities in the iron are essential for the production of Damascus blades?

A、 There are surface features of every Damascus blade—including the blades produced by the contemporary sword maker—that are unique to that blade.
B、 The iron with which the contemporary sword maker made Damascus blades came from a source of iron that was unknown two centuries ago.
C、 Almost all the tools used by the contemporary sword maker were updated versions of tools that were used by sword makers over two centuries ago.
D、 Production of Damascus blades by sword makers of the past ceased abruptly after those sword makers' original source of iron became exhausted.
E、 Although Damascus blades were renowned for maintaining a sharp edge, the blade made by the contemporary sword maker suggests that they may have maintained their edge less well than blades made using what is now the standard process for making blades.

【正确答案】 D

【答案解析】Argument Evaluation
Situation A sword maker may have recently rediscovered how to make Damascus blades using iron with trace impurities matching those in the iron from which historic Damascus blades were wrough .
Reasoning What evidence would suggest that the trace impurities are essential for producing Damascus blades? The passage says the sword maker seems to have created blades indistinguishable from historic Damascus blades by using iron with the same trace impurities found in those blades. But that does not prove the trace impurities are essential to the process. Evidence suggesting that Damascus blades have never been made from iron without the trace impurities would support the hypothesis that the trace impurities are essential to their manufacture.
A Damascus blades could vary in their surface features whether or not trace impurities are essential for their manufacture.
B Whatever the source of the iron the contemporary sword maker used, it contains the same trace impurities as the iron historically used to make Damascus blades, which is what the hypothesis is about.
C If anything, this might cast doubt on the hypothesis by suggesting that the special tools rather than the trace impurities could account for the distinctive features of Damascus blades.
D Correct. This suggests that when the historic sword makers lost access to the special iron with its trace impurities, they could no longer make Damascus blades. Thus, it supports the hypothesis that the trace impurities are necessary for manufacturing Damascus blades.
E Even if Damascus blades maintained their edges less well than most contemporary blades do, the trace impurities may not have been essential for manufacturing them.
The correct answer is D.