单选题 How long you live has a lot to do with your environment and lifestyle, but exceptional longevity may have even more to do with your genes. For the first time, researchers have identified a genetic recipe that accurately predicts who may live to 100 and beyond. Scientists led by Dr. Thomas Perls at the Boston University School of Medicine conducted a genetic analysis of more than 1,000 centenarians and their matched controls and found 150 genetic variants--or bits of DNA--that differed between the two groups. These variants identified people who lived to a very old age (past 100) with 77% accuracy, researchers found.
Further analysis identified 19 distinct genetic profiles associated with extremely long life; 90% of participants who lived to 100 possessed at least one of the signature genetic clusters. Each profile appeared to confer a different tendency to develop common age-related chronic diseases, such as heart disease or brain disorder. "We realize this is a complex genetic puzzle," Perls said. "We're quite a ways away still in understanding how the integration of these genes--not just with themselves but with environmental factors--are playing a role in this longevity puzzle."
Perls has studied many factors that contribute to longevity, and he is the first to acknowledge that living longer isn't likely to be simply a matter of genes. His previous work has shown, for example, that among most elderly people who live into their 70s and 80s, about 70% of their longevity can be ascribed to environmental factors such as not smoking; eating a healthy, low-fat, low-calorie diet; and remaining socially engaged and intellectually active throughout life.
Still, it seems clear that those who live to an exceptionally ripe old age are benefiting from a special DNA boost. In fact, Perls believes that the older a person gets, the more likely it is that his or her genes are contributing to those extended years. His current genetic findings support that theory: the 19 most common genetic profiles that distinguished the exceptionally long-lived appear to be correlated with lower incidence of certain diseases. For example, some profiles were associated with lower rates of high blood pressure and diabetes, while another was linked to a reduced risk of brain disorder.
Although most of us can't expect to become centenarians, Perls is hoping that his work will lead to better ways--perhaps through pharmaceutical interventions based on the genetic clues to longevity--to help more of us live like them.

【正确答案】 C

【答案解析】细节理解题。根据题干定位到第1段。本段最后一句讲到科学家发现某些基因变异体能够在某种程度上鉴别特别长寿者，故C项与之相符。A项是文章开头的一般说明，并非科学家的主要发现；B项与原文相悖，特别长寿者的某些基因不同寻常；D项曲解文意，百岁老人并非是具备19个不同于常人的基因图谱，而是至少拥有这19个基因图谱中的某种标志基因组。