How do modern political parties typically choose electors?

Modern political parties typically choose electors through a popular election, which is why this option is correct. In the United States, when citizens cast their votes for president, they are actually voting for a slate of electors pledged to that candidate. This process varies by state, but generally, voters participate in a general election where they select their preferred candidates.

At the conclusion of the election, the electors who are chosen are those who represent the outcome of the popular vote in that state. This method solidifies the democratic principle of directly engaging citizens in the electoral process, as they have a direct voice in determining which electors will cast votes in the Electoral College.

The other choices do not reflect the standard practice across the nation. Legislative votes or appointments from party leaders do not generally play a role in the electors' selection, as the intention is to maintain a system where voter preference guides the electoral process. Similarly, state courts do not determine how electors are selected; rather, they oversee legal matters but do not involve themselves in the election mechanics in this context.