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题目材料：
The element ytterbium increases its electrical resistance when subject to high mechanical stresses. This property has made it an indispensable component in a medical tool designed to measure the stress on bones, which can guide physicians in setting broken bones. Unfortunately, ytterbium is rare, found in only a few meager sources around the world. A steep market demand will cause the price to skyrocket, and this technology so helpful to physicians will become unaffordable.
Which of the following, if true, most seriously weakens the argument above?
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A.Just one mining company controls all the ytterbium that is imported into the United States, where these medical tools are manufactured.
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B.The process of extracting pure ytterbium from its ores, euxenite and xenotime, is very expensive and involves strong acids.
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C.Ytterbium is also used as an additive, in small quantities, in the manufacture of stainless steel and solid-state lasers.
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D.Some common alloys of tin also increase their electrical resistance under mechanical loads.
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E.The largest source of ytterbium is in a relatively remote region of China.
D显示答案
