Which Aspect of Niche Online Social Networks Makes the Medium

Which aspect of niche online social networks makes the medium most appealing to marketers?

A) They help marketers target the best undifferentiated market segment.
B) They are used by a majority of Internet users in the U.S. and overseas.
C) They cater to the needs of small communities of like-minded people.
D) They guide organizations on how to set up social media networks.
E) They allow marketers to control the conversations on the network.