单选题 When a stone is trimmed by a mason and exposed to the elements, a coating of clay and other minerals, called rock varnish, gradually accumulates on the freshly trimmed surface. Organic matter trapped beneath the varnish on stones of an Andean monument was found to be over 1,000 years old. Since the organic matter must have grown on the stone shortly after it was trimmed, it follows that the monument was built long before the arrival of Europeans in the Americas in 1492.
Which one of the following, if true, most seriously weakens the argument?

A、 Rock varnish itself contains some organic matter.
B、 The reuse of ancient trimmed stones was common in the Andes both before and after 1492.
C、 The Andean monument bears a striking resemblance to monuments found in ancient sites in western Asia.
D、 The earliest written reference to the Andean monument dates from 1778.
E、 (E) Rock varnish forms very slowly, if at all, on trimmed stones that are stored in a dry, sheltered place.

【正确答案】 B

【答案解析】[解析] 本题论述的结论很显然是以用于建造安迪斯纪念碑的石头是在修建纪念碑时修整的为前提。(B)否定了该前提，因此(B)为正确答案；(A)、(C)、(D)和(E)均为无关选项。