Which of the Following Best Defines Aggregators

Which of the following best defines aggregators?

A) They include search engine sites that develop little new content but mostly direct users elsewhere.
B) They include newspaper sites that hire journalists and create new material.
C) They are online activists who support the candidate but are not controlled by the candidate's organization.
D) They are political candidate's press advisers who try to convince reporters to give a story or event concerning the candidate a particular "spin."
E) They are hired by candidates to manage their campaigns.