Passage oneQuestions 46 to 50 are based on the following passageAging happens to all of us ,and is generylly thought of as a natural part of life. It would seem silly to call such a thing a "disease".on the other hand,scientists are increasingly learning that aging and biological age are two different things,and that the former is a key risk factor for conditions such as heart disease,cancer and many more. in that light,aging itself might be seen as something treatable, the way you would treat high blood pressure or a vitamin deficiency.Biophysicist alex zhavoronkov believes that aging should be considered a disease. he said that describing aging as a disease creates incentives to develop treatments."It unties the hands of the pharmaceutical(制药的)industry so that they can begin treating the disease and not just the side effects, "he said。"Right now, people think of aging as natural and something you can't control "he said. "in academic circles, people take aging research as just an interest area where they can try to develop interventions. the medical community also takes aging for granted, and can do nothing about it except keep people within a certain health range."But if aging were recognized as a disease, he said, "it would attract funding and change the way we do health care. what matters is understanding that aging is curable. ""it was always known that the body accumulates damage, "he added. "the only way to cure aging is to find ways to repair that damage. i think of it as preventive medicine for age-related conditions.Leonard hayflick, a professor at the university of califomia, san francisco, said the idea that aging can be cured implies the human lifespan can be increased, which some researchers suggest is possible. hayflick is not among them." There 're many people who recover from cancer, stroke or heart disease. but they continue to age, because aging is separate from their disease, " said."even if those causes of death were eliminated, life expectancy would still not go much beyond 92 years." how do many scientists view aging now?（）

A. it might be prevented and treated
B. it can be as risky as heart disease
C. results from a vitamin deficiency
D. it is an irreversible biological proces