The correct ansewer is to sway an opinion.
The idea that describes the point of propaganda is: to sway an opinion. Propaganda tries to influence public opinion.
What propaganda does is create an idea, a different connotation o negative reputation of a situation or public figure in order to sway the public opinion, damage or destroy the public image of the person or the situation. In extreme cases, to finish the career of a politician.
During war times, Propaganda helped rally support for government efforts to use military actions. Today, propaganda in generated via Public Relations or Advertising agencies and their work is manifested politic speeches, advertising in Mass Media, books ore ven films.