In an open primary, which voters are allowed to vote in any party's primary or caucus?

• A. Only registered with a party
• B. Only party members
• C. Any registered voter may vote in any party's primary or caucus
• D. Independents cannot vote

Answer: (C)

Open primaries let registered voters participate in any party’s primary or caucus, regardless of their own party registration. The defining idea is cross-party access: you can choose which party’s ballot to vote with on primary day, whether you’re registered with a party or not. That’s why this option—any registered voter may vote in any party’s primary or caucus—best captures how open primaries work. In contrast, closed systems limit participation to the party’s own members or registered supporters, which is not how open primaries operate. Note that some states have variations like semi-open or semi-closed rules, but the core concept remains that open primaries allow voters to participate across party lines.