Twenty percent of the residents of Green City are members of minority racial groups. These residents are evenly distributed among the many different residential areas of the city. The five city council members of Green City are elected from five single-member electoral districts that are nearly equally populated. No candidate has ever been elected to the city council who was a member of a minority racial group. A group of citizens who are members ofminority racial groups file suit in federal district court seeking a declaratory judgment that the single-member districts in Green City are unconstitutional. They claim that the single-member districting system in that city diminishes the ability of voters who are members of minority racial groups to affect the outcome of city elections. They seek an order from the court forcing the city to adopt an at-large election system in which the five candidates with the greatest vote totals would be elected to the city council. No state or federal statutes are applicable to the resolution of this suit. Which of the following constitutional provisions provides the most obvious basis for plaintiffs' claim in this suit?
The Thirteenth Amendment. The due process clause of the Fourteenth Amendment. The privileges and immunities clause of the Fourteenth Amendment. The Fifteenth Amendment.