题目选项分析

Several of a certain bank's top executives have recently been purchasing shares in their own bank. This activity has occasioned some surprise, since it is widely believed that the bank, carrying a large number of bad loans, is on the brink of collapse. Since the executives are well placed to know the bank's true condition, it might seem that their share purchases show that the danger of collapse is exaggerated. However, the available information about the bank's condition is from reliable and informed sources, and corporate executives do sometimes buy shares in their own company in a calculated attempt to calm worries about their company's condition. On balance, therefore, it is likely that the executives of the bank are following this example.

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

【选项】Each provides evidence to support the position that the argument seeks to establish.