Which of the Following Implications Does Social Media Pose on Marketers

Which of the following implications does social media pose on marketers?

A) Marketers must understand that social media lacks methods to measure the interaction between marketers and customers.
B) Marketers must understand that word of mouth spreads slowly on social media sites.
C) Marketers must realize that it is enough for them to have a great ad campaign on social media for successful promotion.
D) Marketers must realize that they often do not control the content on social media sites.