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.