单项选择题

Passage Two

Social scientists distinguish between what are known as treatment effects and selection effects. The Marine Corps, for instance, is largely a treatment-effect institution. It is confident that the experience of undergoing Marine Corps basic training will turn you into a formidable soldier. A modeling agency, by contrast, is a selection-effect institution. You do not become beautiful by signing up with an agency. At the heart of the American obsession with the Ivy League is the belief that schools like Harvard provide the social and intellectual equivalent of Marine Corps basic training—that being taught by all those brilliant professors and meeting all those other motivated students and getting a degree with that powerful name on it will confer advantages that no local state university can provide, and even an Ivy Leaguer will make far more money in the future. It is quite possible that the student who goes to Harvard is more ambitious and energetic and personable than the student who was not let in. Three years ago, the economists Alan Krueger and Stacy Dale published just such a study. And they found that when you compare apples with apples, the income bonus from selective schools disappears. "As a Hypothetical(假设的) example, take the University of Pennsylvania and Penn State," Krueger said. "One is Ivy; one is a state school. Penn is much more highly selective. You would think that the more ambitious student is the one who would choose to go to Penn, and the ones choosing to go to Penn State might be a little less confident in their abilities or have a little lower income, and both of those factors would point to people doing Worse later on. But they don’t. " Krueger says, "There is one exception to this." If you are a hardworking and intelligent person you will end up doing well regardless of where you graduate. You will make good contacts at Penn. But Penn State is big enough and diverse enough that you can make good contacts there, too. With Penn on your resume opens doors. But if you are good enough, those doors will open for you anyway.

It is implied in the first paragraph that ______.