题目选项分析

Since it has become known that several of a bank's top executives have been buying shares in their own bank, the bank's depositors, who had been worried by rumors that the bank faced impending financial collapse, have been greatly relieved. They reason that, since top executives evidently have faith in the bank`s financial soundness, those worrisome rumors must be false. Such reasoning might well be overoptimistic, however, since corporate executives have been known to buy shares in their own company in a calculated attempt to dispel negative rumors about the company's health.

In the argument given, the two boldfaced portions play which of the following roles?

【选项】The first describes the circumstance that the argument as a whole seeks to explain; the second gives the explanation that the argument seeks to establish.