frivolous :- not having any serious purpose or value.

Adolescents--->large weekly allowances-->spend on items not having any serious purpose or value.

Adolescents--->small weekly allowances-->do not spend on items not having serious purpose or value.

The conclusion of the passage is that parents can ensure that their children will not spend money on frivolous items by limiting their children's allowances. This claim is based on the observed difference between the spending habits of children who receive large allowances and those of children who receive small allowances. The argument assumes that the high dollar amount of the allowance – as opposed to some other unobserved factor – is directly linked to the fact that children spend the money on items their parents consider frivolous. Information that provides data about any other factor that might be the cause of the children's spending behavior would help to evaluate the validity of the conclusion.

(B) CORRECT. One alternative to the conclusion of the passage is that the standard used to judge an item as frivolous was much lower for parents who gave their children large weekly allowances than for parents who gave their children small weekly allowances. If for example, the former group of parentsconsidered all movie tickets to be frivolous, while the latter did not, then this fact (and not the difference in allowance money) might explain the difference observed by the child development specialists. Thus, information about any differences among parents in the standard used to judge an item as frivolous would be extremely relevant in evaluating the validity of the conclusion of the passage.

(C) The background of the child development specialists who made the observation has no bearing on the conclusion. The conclusion is based on the observation, not on the credentials of those making the observation.

(D) Family income differences have no clear relevance to the link posited between high allowances and spending on frivolous items.