资料题：Which of the following statements is true（　）。

It is predicted that there will be 5 scientific breakthroughs in the 21st century.We'll know where we came from.Why does the universe exist? To put it another way, why is there something instead of nothing? Since the 1920s, scientists have known the universe is expanding, which means it must have started at a.definite time in the past.They even have developed theories that give a detailed picture of the evolution of the universe from the time it was a fraction of a second old to the present.We will have a better understanding of how matter behaves at the unfathomably(难以估量的)high temperatures and pressures of the early universe.We'll crack the genetic code and conquer cancer.As scientists learn more about the genetic code and the way cells work at the molecular level, many serious diseases-cancer, for one-will become less threatening.Using manufactured "therapeutic" (治疗的) viruses , doctors will be able to replace cancer with healthy genes , probably administered by a pill or injection.We' II live longer (120 years?)21st-century strides in genetic medicine may let us control and even reverse the process.But before we push scientists to do more, consider:Do we really want to live in a world where no one grows old and few children are born because the planet can hold only so many people? Where would new ideas come from? What would we do with all that extra time?We'll "manage" Earth.In the next millennium, we'll stop talking about the weather but will do something about it.We'll gradually learn how to predict the effects of human activity on the Earth, its climate and ts ecosystems.We'll have a brain "road map".Early in the next century, we will use advanced forms of magnetic resonance to produce detailed maps of the neurons in operation.We'll be able to say with certainty which ones are working when you read a wand, when you say a wand, why you think about a ward, and so on.