Which system is most likely to limit the concentration and effect of minority votes?

The most appropriate answer is that at-large voting systems can limit the concentration and effect of minority votes. In an at-large voting system, representatives are elected by the entire voting population of a jurisdiction rather than from specific geographic districts. This often leads to a situation where the majority can dominate the election outcomes, as all voters contribute to the selection of representatives without the ability to elect candidates that may represent smaller community interests or minority populations.

In contrast, proportional representation and ranked-choice voting are designed to give more voice to minority groups by allowing for a distribution of votes that reflects the electorate more equitably. Single-member districts can also enhance representation for minorities, as they allow these groups to consolidate their votes in specific areas, increasing the likelihood of electing candidates who represent their interests. Thus, at-large voting is the system that most likely diminishes the influence of minority voters.