题目：
The most popular organic gem is the pearl. A pearl is the response of a marine mollusk to the presence of an irritating impurity accidentally introduced into its body; a cultured pearl is the result of the intentional insertion of a mother-of-pearl bead into a live mollusk. Whether introduced accidentally or intentionally, the pearl-making process is the same: the mollusk coats the irritant with a substance called nacre. Nacre is composed chiefly of calcium carbonate. Because very few natural pearls are now on the market, most pearls used in fine jewelry are cultured. These include "Biwa" pearls and most other freshwater pearls. Cultured pearls are not easily distinguished from natural pearls except by an expert.
Which of the following people could tell the difference between a cultured pearl and an organic pearl
A．Scuba diver.
B．Fisherman.
C．Jeweler.
D．Clerk.
答案：
参考答案：C
解析：细节题型。见文章最后一句：Cultured pearls are not easily distinguished from natural pearls except by an expert．只有专家才能区分出天然珍珠和人工培育的珍珠。珠宝商当然应是这类专家，所以选项C正确。A．Scuba diver戴水肺的潜水员B．Fisherman渔民和D．Clerk职员当然不是鉴别珠宝的行家了。
