单项选择题

TEXT A
A century ago, a cut or even a decayed tooth were causes for alarm, as they could lead to pneumonia, against which doctors could only offer home-made cures, crude surgery or, finally, their prayers. Today, these perils have been stopped by the medical weapons of 20th century—and as a result, man has the potential for living longer than at any time in history. In the past 100 years, the life expectancy in a developed country has almost doubled. Researchers believe the millennium will usher in Century of Biotechnology, as computing power and knowledge of the genetic code come together.
Here are come of the biggest developments in medicine that can be expected over the next quarter-century.
1. Diagnosing ailments will be simpler, faster, more accurate and cheaper, using noninvasive scanners, teleconferencing and the Internet. Farther down the track—perhaps 10～15 years—are biochips, which will monitor your DNA and analyze it for genetic anomalies that could bring you fatal diseases or have and adverse reaction to certain drugs. You could then make lifestyle changes enabling you to avoid exposure to conditions or substances known to trigger the disease.
2. Advances in molecular biology mean that scientists now know more than ever about the genetic causes of disease and how to garget them. Over the next decade or so, enzyme inhibitors and gene therapy will make great inroads against different kinds of cancer, heart disease and even brain diseases such as Alzheimer’s. The surgeon of the future may look back on the present ear with the same sense of distaste as his present counterpart views the blood-soaked sawbones of the 19th century. In the coming decades, surgery will be carried out only as a last resort and as minimally as possible. Robots will help perform long or tricky operations such as organ transplants. Nano-probes may be used to clear the arteries free of dangerous plaque build-ups. Another possibility: microchip implants and transplants into the central nervous system to help treat disease like brain tumors, epilepsy, movement disorders and stroke.
3. Outbreaks of disease that previously were localized have the ability to spread quickly, thanks to modern jet travel; a person incubating a new strain of flu in one continent can take it to another in a matter of hours. In addition, feeding and housing a population of six billion has brought Man into closer and closer proximity to animals and rain forests, exposing humans to viruses that "leap" the species barrier, such as mad-cow disease and hemorrhagic fever.
On the hand, microbiology and epidemiology are so advanced that scientists can now quickly spot a new disease (AIDS was detected only three years after it was fist identified) and find out how it is transmitted. This can help in the development of preventative measures, although finding a cure or a vaccine are different matters, as the elusive search for a "silver bullet" against AIDS has shown. In wealthy western countries, the risk to life may be lifestyle. Obesity and depression, caused by excessive eating, loneliness and alienation, may become the twin biggest causes of death. (518 words)
Why does the author mention the discovery of AIDS in the last paragraph