Passage 1
In his book The Tipping Point,Malcolm Gladwell argues that"social epidemics"are driven in?large part by the actions of a tiny minority of special individuals,often called influentials,who are?unusually informed,persuasive,or well-connected．The idea is intuitively compelling,but it doesn′t?explain how ideas actually spread．
The supposed importance of influentials derives from a plausible-sounding but largely untested?theory called the"two-step flow of communication":Information flows from the media to the?influentials and from them to everyone else．Marketers have embraced the two-step flow because it?suggests that if they can just find and influence the influentials,those selected people will do most of?the work for them．The theory also seems to explain the sudden and unexpected popularity of certain?looks,brands,or neighborhoods．In many such cases,a cursory search for causes finds that some?small group of people was wearing,promoting,or developing whatever it is before anyone else paid?attention．Anecdotal evidence of this kind fits nicely with the idea that only certain special people?can drive trends．
In their recent work,however,some researchers have come up with the finding that influentials?have far less impact on social epidemics than is generally supposed．In fact,they don′t seem to be?required of all．
The researchers′argument stems from a simple observation about social influence:With the?exception of a few celebrities like Oprah Winfrey--whose outsize presence is primarily a function of?media,not interpersonal,influence--even the most influential members of a population simply don′t?interact with that many others．Yet it is precisely these non-celebrity influentials who,according to?the two-step-flow theory,are supposed to drive social epidemics,by influencing their friends and?colleagues directly．For a social epidemic to occur,however,each person so affected must then?influence his or her own acquaintances,who must in turn
A.serves as a solution to marketing problems
B.has helped explain certain prevalent trends
C.has won support from influentials
D.requires solid evidence for its validity