题目内容：
回答题：Thousands of years ago man used handy rocks for his su’gical operations．Laterhe used sharpbones or horns，metal knives and more recently，rubber and plastiC．In the 1960s a new tool wasdeveloped，one which was，firstof all，to be of great practk al use to the arrnedforces and indus—try，but which was also torevolutionize the art and science c f surgery．
The toolis the laser and it is being used by more and moie surgeons all over the world．Asweall know，light is hot，and anysource of light will give warmth．But light is usuallyspread outover a wide area．The light in a laser beam，however，is concentrated．This means that a light withno more power than that produced by anordinary electric ligl tt bulb becomes intensely strong as itis concentrated toa pinpoint-sized beam．
Experiments with these pinpoint beams showed researchers that differentenergy sources pr0—duce beams that have a particular effect on certain livingcell：．It is now possible for eye surgeonsto operate on the back ofhumaneye without harming the fronl of the eye，simply bypassing a laserbeam fight through the eye—ball．Operationswhich once left patients exhausied and in need of longperiod of recovery timenow leave them feeling relaxed and(9mfortable．
The rapiddevelopment of laser techniques in the past ten years has made it clear thatthe futureis likely to be very exciting．Perhaps some cancers willbe treated with laser in a way that makessurgery not only safer but also moreeffective．
Which of the following would beappropriate to descJ be the instruments of surgical operations up until 1960s? A．Traditional．
B．Complicated．
C．Re narkable．
D．Revolutionary．
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