Come on—Everybody’s doing it. That whispered message, half invitation and half forcing, is what most of us think of when we hear the words peer pressure. It usually leads to no good—drinking, drugs and casual sex. But in her new book Join the Club, Tina Rosenberg contends that peer pressure can also be a positive force through what she calls the social cure, in which organizations and officials use the power of group dynamics to help individuals improve their lives and possibly the world.

    Rosenberg, the recipient of a Pulitzer Prize, offers a host of examples of the social cure in action: In South Carolina, a state-sponsored antismoking program called Rage Against the Haze sets out to make cigarettes uncool. In South Africa, an HIV-prevention initiative known as LoveLife recruits young people to promote safe sex among their peers.

    The idea seems promising, and Rosenberg is a perceptive observer. Her critique of the lameness of many public-health campaigns is spot-on: they fail to mobilize peer pressure for healthy habits, and they demonstrate a seriously flawed understanding of psychology. “Dare to be different, please don’t smoke!” pleads one billboard campaign aimed at reducing smoking among teenagers—teenagers, who desire nothing more than fitting in. Rosenberg argues convincingly that public-health advocates ought to take a page from advertisers, so skilled at applying peer pressure.

    But on the general effectiveness of the social cure, Rosenberg is less persuasive. Join the Club is filled with too much irrelevant detail and not enough exploration of the social and biological factors that make peer pressure so powerful. The most glaring flaw of the social cure as it’s presented here is that it doesn’t work very well for very long. Rage Against the Haze failed once state funding was cut. Evidence that the LoveLife program produces lasting changes is limited and mixed.

    There’s no doubt that our peer groups exert enormous influence on our behavior. An emerging body of research shows that positive health habits—as well as negative ones—spread through networks of friends via social communication. This is a subtle form of peer pressure: we unconsciously imitate the behavior we see every day.

    Far less certain, however, is how successfully experts and bureaucrats can select our peer groups and steer their activities in virtuous directions. It’s like the teacher who breaks up the troublemakers in the back row by pairing them with better-behaved classmates. The tactic never really works. And that’s the problem with a social cure engineered from the outside: in the real world, as in school, we insist on choosing our own friends.

答案精析：根据题干中the first paragraph和peer pressure可定位至原文第一段第二、三句。原文第三句中It指代peer pressure，原文明确指出同辈压力usually leads to no good（经常导致不好结果），破折号后进行进一步解释：drinking, drugs and casual sex（酗酒、吸毒和滥交），D选项中的undesirable behaviors（不良行为）是对此的概括总结，故D选项为正确答案。

错项排除：原文提到罗森伯格认为同辈压力可以作为社会疗法的positive force（正面力量），并非supplement（补充），并且这只是罗森伯格的个人观点，故A选项错误。只有在社会疗法中，group dynamics（群体动态）才能作为stimulus（刺激因素），且这同样只是罗森伯格个人观点，故B选项错误。原文虽提及通常同辈压力会导致不良行为，但并未提及会阻碍社会进步，C选项属于过度推断，故错误。