单选题

Passage1     Come on-Everybody'sdoing it. That whispered message, half invitation and half forcing, is  what most of us think of when we hear thewords peer pressure. It usually leads to no good-drinking, drugs and casualsex. But in her new book Join the Club, Tina Rosenberg contends that  peer pressure can also be a positive forcethrough what she calls the social cure, in which organizations and officialsuse the power of group dynamics to help individuals improve their lives andpossibly the word.     Rosenberg, therecipient of a Pulitzer Prize, offers a host of examples of the social cure inaction: In South Carolina, a state-sponsored antismoking program called RageAgainst the Haze sets  out to make cigarettesuncool. In South Africa, an HIV-prevention initiative known as loveLife  recruits young people to promote safe sexamong their peers.      The idea seemspromising, and Rosenberg is a perceptive observer. Her critique of the lamenessof many pubic-health campaigns is spot-on: they fail to mobilize peer pressurefor healthy habits ,and they demonstrate a seriously flawed understanding of psychology.   Dare to be different, please don'tsmoke! pleads one billboard campaign aimed at reducing smoking amongteenagers-teenagers, who desire nothing more than fitting in. Rosenberg arguesconvincingly that public-health advocates ought to take a page from advertisers, so skilled at applyingpeer pressure.      But on the generaleffectiveness of the social cure, Rosenberg is less persuasive. Join the Clubis filled with too much irrelevant detail and not enough exploration of thesocial and biological factors that make peer pressure so powerful. The mostglaring flaw of the social cure as it's presented here is that it doesn't workvery well for very long. Rage Against the Haze failed once state funding wascut. Evidence that the loveLife program produces lasting changes is limited andmixed.      There's no doubtthat our peer groups exert enormous influence on our behavior. An emerging bodyof research shows that positive health habits-as well as negative ones-spreadthrough networks of friends via social communication. This is a subtle form ofpeer pressure: we unconsciously imitate the behavior we see every day.     Farless certain, however, is how successfully experts and bureaucrats can selectour peer groups and steer their activities in virtuous directions. It's likethe teacher who breaks up the troublemakers in the back row by pairing themwith better-behaved classmates. The tactic never really works. And that's theproblem with a social cure engineered from the outside: in the real world, asin school, we insist on choosing our own friends.The author suggests in the last paragraph that the effect of peer pressure is_______.

A harmful

B desirable

C profound

D questionable

解析：