Social Networks Can Influence People Through Contagion

Social networks can influence people through contagion.What does that mean?

A) When connection leads to disease or infection, sociologists call it contagion.
B) The influence of various social networks is contagious. Networks tend to mimic each other over the long run.
C) This borrows from a biological model: if people are weak, they are likely to "catch" the influence of their social network.
D) When people are connected to a social network, what happens in that network is more likely to affect them.