下列关于图中所示光学现象的描述或解释正确的是：（）

    Do you want to live another 100 years or more? Some experts say that scientific advances will one day enable humans to last tens of years beyond what is now seen as the natural limit of the human life span.

    “I think we are knocking at the door of immortality (永生),” said Michael Zey, a Montclair State University business professor and author of two books on the future. “I think by 2075 we will see it and that's a conservative estimate (保守的估计).”

    At the conference in San Francisco, Donald Louria, a professor at New Jersey Medical School in Newark said advances in using genes as well as nanotechnology (纳米技术) make it likely that humans will live in the future beyond what has been possible in the past. “There is a great effort so that people can live from 120 to 180 years,” he said. “Some have suggested that there is no limit and that people could live to 200 or 300 or 500 years.”

    However, many scientists who specialize in aging are doubtful about it and say the human body is just not designed to last past about 120 years. Even with healthier lifestyles and less disease, they say failure of the brain and organs will finally lead all humans to death.

    Scientists also differ on what kind of life the super aged might live. “It remains to be seen if you pass 120, you know; could you be healthy enough to have good quality of life?” said Leonard Poon, director of the University of Georgia Gerontology Centre. “At present people who could get to that point are not in good health at all.”

阅读下面短文，完成小题。
                                                                                             回家去问妈妈
                                                                                                  毕淑敏
         ①那一年游敦煌回来，兴奋地同妈妈谈起戈壁的黄沙和祁连的雪峰。说到丝绸之路上僻远的安西，哈密瓜汁甜得把嘴唇粘在一起……一直安静听我说话的妈妈，淡淡地插了一句：“在你不到半岁的时候，我就抱着你走过安西。”我大吃一惊，从未听妈妈谈过这段往事。    
         ②妈妈说，你生在新疆，长在北京。难道你是飞来的不成?以前我一说起带你赶路的事，你就嫌烦，说知道啦，别再啰嗦。
         ③我静静地倾听妈妈的描述，才知道我在幼年时曾带给母亲那样的艰难。才知道发生在安西的感动源远流长。突然意识到，在我和最亲的母亲之间，潜伏着无数盲点。
         ④我们总觉得已经成人。母亲只是一间古老的旧房，她给我们的童年以遮避，但不会再提供新的风景。我们急切地投身外面的世界，寻找自我的价值。全神贯注地倾听上司的评论，字斟句酌地印证众人的口碑，反复咀嚼朋友随口吐露的点滴印象，甚至会为别人一颦一笑的涵意彻夜思索……我们极其在意世人对我们的看法，恰恰忘了，当我们环视整个世界的时候，总有一双微微眯起的眼睛，始终在背后凝视着我们。母亲默默地关注，就像手艺精湛的老艺人，不厌其烦地打磨描绘她们制造的精品。于是我们厌烦了，不客气地说，老提那些过去的事，烦不烦呀?从此，母亲就真的噤了声。
         ⑤蓦然回首，才发现自己远远没有长大。我们幼年的顽皮、成长的艰辛、与生俱来的弱点、异于常人的秉赋……从小到大最详尽的档案、每一次失败与成功的记录，都贮存在母亲宁静的眼中。我们曾经满世界地寻找真诚，却不知最想要的真诚就在母亲那里。
         ⑥我们像一本没有结尾的书，每一个符号都是母亲用血书写。我们还未曾读懂，著者已撒手而去。从此我们面对书中的无数悬念和秘密，无以破译。我们流落世间，成为飘零的红叶。
         ⑦趁老树虬曲的枝丫还郁郁葱葱，让我们赶快跑回家，去问妈妈。
         ⑧一定要赶快啊!生命给我们的允诺并不慷慨，两代人命运的云梯衔接处，时间只是窄窄的台阶。从我们明白人生的韵律，距父母还能明晰地谈论以往，并肩而行的日子屈指可数。
         ⑨给母亲一个机会，让她重温创造的喜悦；给儿女一个机会，让我们深刻洞察尘封的的记忆。     (选文有删改)