题目选项分析

Weight loss programs that guarantee results mislead their customers. No program can ensure that someone who follows it will lose weight. These programs prey upon unhappy and insecure people who are often driven more by emotion than by reason. Moreover, many people who lose weight while on a program eventually regain the weight within a year. So while the programs' claims may be true for a short period, customers will be disappointed in the long run.

The two portions in boldface play which of the following roles?

【选项】The first is evidence in support of the author's main point; the second is the author's main point.