D
Aroca City currently funds its public schools through taxes on property. <b> In place of this system, the city plans to introduce a sales tax of 3 percent on all retail sales in the city. </b> Critics protest that 3 percent of current retail sales falls short of the amount raised for schools by property taxes. The critics are correct on this point. <b> Nevertheless, implementing the plan will probably not reduce the money going to Aroca' s schools. </b>Several large retailers have selected Aroca City as the site for huge new stores, and these are certain to draw large numbers of shoppers from neighboring municipalities, where sales are taxed at rates of 6 percent and more. In consequence, retail sales in Aroca City are bound to increase substantially. In the argument given, the two portions in <b> boldface </b> play which of the following roles?
A: The first presents a plan that the argument seeks to defend against a certain criticism; the second is that criticism.
B: The first presents a plan that the argument contends is the best available; the second is a conclusion drawn by the argument to justify that contention.
C: The first presents a plan that the argument concludes is unlikely to achieve its goal; the second expresses that conclusion.
D: The first presents a plan one of whose consequences is at issue in the argument; the second is the argument's conclusion about that consequence.