题目选项分析

Newsletter: A condominium generally offers more value for its cost than an individual house because of economies of scale. The homeowners in a condominium association can collectively buy products and services that they could not afford on their own. And since a professional management company handles maintenance of common areas, condominium owners spend less time and money on maintenance than individual homeowners do.

The two portions in boldface play which of the following roles in the newsletter's argument?

【选项】Both are premises, for which no evidence is provided, and both support the argument's only conclusion.