题目选项分析

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?

【选项】The iron with which the contemporary sword maker made Damascus blades came from a source of iron that was unknown two centuries ago.