Which Is One Difference Between Mass Media and Social Media

Which is one difference between mass media and social media?

A) Social media is one-way, while mass communication is two-way.
B) The purpose of mass media is entertainment, while the purpose of social media is information.
C) With mass media the audience is mostly unknown, while with social media the audience is mostly known.
D) With social media the source provider controls the content, while with mass media the senders and receivers control the content.