题目选项分析

Child development specialists have observed that adolescents who receive large weekly allowances tend to spend money on items considered frivolous by their parents whereas adolescents who receive small weekly allowances do not. Thus, in order to ensure that their children do not spend money on frivolous items, parents should not give their children large weekly allowances.

Which of the following pieces of information would be most useful in evaluating the validity of the conclusion above?

【选项】The difference between the average annual income of families in which the parents give their children large weekly allowances and that of families in which the parents give their children small weekly allowances