Why Do Certain Social Media Create a Dilemma for Marketers

Why do certain social media create a dilemma for marketers?

A) Social networks favor public relations tactics, so firms are wondering where to spend their advertising dollars.
B) Internet forums are emerging as an alternative to mass media as a source of information.
C) Marketers generally do not like to use outlets where they cannot pay for message placement.
D) News aggregators are themselves not connectors, so marketers shy away from using these outlets.
E) Online communities are replacing personal sales forces, traditionally the biggest promotional investment for firms.