Which of the following is a key characteristic of the Electoral College system?

A key characteristic of the Electoral College system is that each state has a fixed number of electors, which is determined by the sum of its Senators and Representatives in Congress. This means that smaller states have a minimum of three electors, while larger states have more, reflecting their larger populations. This structure ensures that every state has a voice in the presidential election process, although the total number of electors for each state varies based on its population and representation in Congress.

The other options do not accurately reflect the features of the Electoral College. For example, not all states have the same number of electors; their numbers vary based on population. While electors are indeed chosen in a process that includes popular voting, it is not universal in every state, as some states have variations in how they select electors. Additionally, electors are not required to cast their votes based solely on the national popular vote; they typically pledge to support the candidate who wins the popular vote in their respective states, but there isn't a national mandate that binds them to the overall popular vote outcome.