The fear of the new$100 bill is most widespread in those countries where ( ).

参考解析：

从第三段：The Federal Reserve estimates that two-thirds of all U. S. cash circulates outside the United States. In nations where inflation is high and where there are few credible banking institutions from Latin America to Africa people save and conduct business in$100 bills. And with the U. S. issuing new$100 bills, many abroad are worrying that the ones they already have are about to become worthless. 此题属于细节推断题，这句话中美元的2/3都在美国外流通，这些国家通常通货膨胀，信用银行少，集中在拉美和非洲人群，他们中大多使用100美元面值，如果美国发行新100美元面值，他们知道它们手中的旧版100美元将毫无价值。因此推断出，问题中的fear来自于流通旧版100美元的哪些国家，故本题正确答案选D。