The number of citizens over eighteen.

• A. Voting-eligible population
• B. Beat
• C. Citizen journalism
• D. Voting-age population

Answer: (D)

The main idea here is understanding how researchers describe the size of the electorate using population measures. The phrase “over eighteen” points to people who are at least 18 years old, which defines the voting-age population. This count includes everyone 18 and older, regardless of citizenship or voting eligibility, and it’s the standard metric used to estimate how large the pool of potential voters could be. It’s also used to calculate turnout, for example by comparing the number of votes cast to the voting-age population.

The other terms are about different things: Beat is a journalist’s assigned reporting area, and citizen journalism refers to ordinary people reporting news. Voting-eligible population is more precise, counting only those 18+ who are actually eligible to vote (excluding noncitizens and those disenfranchised, for instance). But given the phrasing about those who are over eighteen, the best match is voting-age population.