How Does Advertising Differ from Public Relations

How does advertising differ from public relations?

A) Advertising reaches its audience through paid media, whereas public relations does not.
B) Public relations is more precise and carefully placed than advertising.
C) Public relations appears just as the advertiser designs it, whereas advertising does not.
D) All public relations messages are openly sponsored, whereas advertising is not.
E) Advertising is a better medium than public relations for building credibility.