GMAT&LSAT CR Test C-9th

9.     Determining the authenticity of purported pre-Columbian artifacts is never easy. Carbon-14 dating of these artifacts is often impossible due to contamination by radioactive palladium (which occurs naturally in the soils of Central and South America). However, historians and anthropologists have evolved two reliable criteria, which, utilized in combination, have proven effective for dating these artifacts. First, because authentic pre-Columbian artifacts characteristically occur in a coarse, granular matrix that is shifted by major earthquakes, they often exhibit the unique scratch patterns known as gridding. In addition, true pre-Columbian artifacts show a darkening in surface color that is caused by centuries of exposure to the minute amounts of magnesium in the soil of the Americas.

The criteria above would be LEAST useful in judging the authenticity of which of the following?

(A) An ax head of black obsidian, unearthed from a kitchen midden

(B) A pottery bowl with a red ocher design, found in the ruins of a temple

(C) A set of gold ear weights, ornamented with jasper pendants

(D) A black feather cape from a king’s burial vault（D）

(E) A multicolored woven sash found near the gravesite of a slave

答案：D。我在A与D之间做了错误的判断:-( 原文是说判断原则有二，第一是exhibit the unique scratch patterns known as gridding，第二是darkening in surface color，需联合考虑作出结论是否是pre-C时代的物品。A与D都直接提到了black，但是都没有直接提到exhibit the unique scratch patterns known as gridding，我认为ax斧子因为被用来劈砍东西所以有scratch的痕迹，cape披肩不一定有类似特征啊。为什么选的是D而不是A呢？还是因为后面挖掘地点的原因导致是D呢？不理解。。。请多多指教：）