Which voting method is primarily concerned with a candidate's future policies?

The correct answer is grounded in the concept of prospective voting, which refers to voters making decisions based on their expectations of a candidate's future policies and actions. In prospective voting, individuals consider how a candidate's proposed policies align with their own values and needs, and they ultimately vote based on their predictions about the future impact of those policies if the candidate is elected.

In contrast, rational choice voting focuses on individuals making choices based on a calculation of personal benefit or utility derived from policies, which can include both present and anticipated outcomes but doesn't singularly emphasize future policies. Party-line voting entails selecting candidates based primarily on their party affiliation rather than policy implications, so it does not focus on future policy considerations. Retrospective voting is based on evaluating a candidate’s past performance and policies, leading voters to make choices reflecting their satisfaction or dissatisfaction with what has already occurred rather than what might happen in the future.

Thus, the emphasis of prospective voting on future policies distinctly sets it apart from the other methods of voting, confirming it as the most appropriate choice in this context.