单项选择题

TEXT C
To live in the United States today is to gain an appreciation for Dhrendorf’s assertion that social change exists everywhere. Technology, the application of knowledge for practical ends, is a major source of social change.
Yet we would do well to remind ourselves that technology is a human creation; it does not exist naturally. A spear or a robot is as much a cultural as a physical object. Until humans use a spear to hunt game—or a robot to produce machine parts, neither is much more than a solid mass of matter. For a bird looking for an object on which to rest, a spear or robot serves the purpose equally well. The explosion of the Challenger space shuttle and the Russian nuclear accident at Chernobyl drive home the human quality of technology; they provide cases in which well-planned systems suddenly went haywire and there was no ready hand to set them right. Since technology is a human creation, we are responsible for what is done with it. Pessimists worry that we will use our technology eventually to blow our world and ourselves to pieces. But they have been saying this for decades, and so far we have managed to survive and even flourish. Whether we will continue to do so in the years ahead remains uncertain. Clearly, the impact of technology on our lives deserves a closer examination.
Few technological developments have had a greater impact on our lives than the computer revolution. Scientists and engineers have designed specialized machines that can do the tasks that once only people could do. There are those who assert that the switch to an information-based economy is in the same camp as other great historical milestones, particularly the Industrial Revolution. Yet when we ask why the Industrial Revolution was a revolution, we find that it was not the machines. The primary reason why it was a revolutionary is that it led to great social change. It gave rise to mass production and, through mass production, to a society in which wealth was not confined to the few.
In somewhat similar fashion, computers promise to revolutionize the structure of American life, particularly as they free the human mind and open new possibilities in knowledge and communication. The Industrial Revolution supplemented and replaced the muscles of humans and animals by mechanical methods. The computer extends this development to supplement and replace some aspects of the mind of human beings by electronic methods It is the capacity of the computer for solving problems and making decisions that represents its greatest potential and that poses the greatest difficulties in predicting the impact on society. (440 words)
The examples of the Challenger and the Chernobyl are cited in the passage to show that ______.