Which late 19th century industry would have the greatest impact on the 20th and 21st centuries

the correct answer is d: "party organizers, volunteers, voters, and elected officials."

party organizers: individuals responsible for designing strategies in order to better execute the political campaign. this includes the candidate's public relations. volunteers: individuals responsible for raising awareness regarding the candidates running for office.voters: individuals who are convinced by volunteers that a particular candidate is the best option.elected officials: winning candidate and his elected team are a product of a successful political campaign.