Final answer:
The primary heuristic on which people rely when voting is party identification, with voters often choosing candidates based on the political party they belong to. Party ID serves as a cue, particularly in elections with limited information about the candidates.
Step-by-step explanation:
The primary heuristic on which people rely when voting is d. party identification. Many voters belong to a political party that represents their political beliefs, and therefore, they often choose candidates based on this affiliation. For instance, a Republican voter might opt for a Republican candidate because of shared conservative values such as a preference for smaller government and lower taxes. Political science research suggests that nearly half of voters depend on their party ID as a cue, especially in elections with limited information about the candidates. Other factors like gender, race, socioeconomic status, and interest-group endorsements can also serve as shortcuts or heuristics in the decision-making process.