[单选题]Passage One Electronic computers are among thefastest and most useful instruments for sorting and comparing in use today.Computers provide the means for greater speed and accuracy in working withideas than had previously been possible. With the development of these newtools it is as if man has suddenly become a millionaire of the mind. Although man has been growing mentallyricher ever since he started to think, the electronic computer allows and willcontinue to allow him to perform tremendous"mental" tasks in arelatively short time. Great scientists of the past produced ideas which werethe basis for great advances, but their ideas sometimes had to wait for yearsbefore they were understood sufficiently well to be of practical use. With thecomputer, the ideas of today's scientists can be studied tested, distributed,and used more rapidly than ever before. Old lines and methods of communication donot work easily or efficiently with as much information as we have now. Therepeated actions of preparing, sorting, filling, distributing: and keepingtrack of records and publications can be as troublesome as calculating. Errorsoccur because men grow tired and can be distracted The basic job of computers is theprocessing of information. For this reason computers can be defined as deviceswhich accept information, perform mathematical or logical operations with theinformation, and then supply the results of these operations as new information. Although a sharp dividing line betweentypes of computers is not always easy to see, computers are usually dividedinto two broad groups: digital and analog. Digital computers work by usingspecific information which is usually the form of numbers. Analog computers onthe other hand, usually process continuous information. To explain this difference, let usconsider two devices which handle information in a manner similar to the twotypes of computers. A turnstile, which has a counter attached to it, can helpto explain the way a digital computer works. Each time a person passes through theturnstile, the indicator quickly jumps from one number to another. Each numberregistered is separate and specific. The continuous change in the level ofsand in an hourglass as time passes makes it an analog device. Perhaps thefirst analog computation was the use of graphs for the solution of surveyingproblems. The word 'distracted'in paragraph 3 means_______ A made unable to move quickly B prevented from talking to others C prevented from doing anything else D made unable to concentrate properly