题目内容：
根据短文内容，回答题。Believe it or not，optical illusion(错觉)can cut highway crashes(撞毁)．Japan is a case in point. It has reduced automobile crashes。n s。me r。ads by nearly 75 percent using a simple. Ptical illusion．Bent strips，called chevrons(人字形)，painted on the roads make drivers think that they are faster than they really are，and thus drivers slow down．
Now the American Automobile Association Foundation for Traffic Safety in Washington D．C．is planning to repeat Japan’s success． Starting next year，the Foundation will paint chevrons and other patterns of 8toips on selected roads around the country to test how well the patterns reduce highway crashes．
Excessive speed plays a major role in as much as one fifth of all fatal(致命)traffic accidents according to the Foundation．To help reduce those accidents，the Foundation will carry its tests in areas where speed-related hazards(危险)are the greatest curves(弯)，exit slopes，traffic circles，and bridges．
Some studies suggest that straight，horizontal bars(水平障碍物)painted across roads can initially(最初)cut the average speed of drivers in half．However，traffic often retums to full speed within months as drivers become used to seeing the painted bars．
Chevrons，scientists say，not only give drivers the impression that they are driving faster than they really are, but also make a lane(车道)appear to be narrower．The result is a longer lasting reduction in highway speed and the number of traffic accidents．
The passage mainly discusses_______． A．a new way of highway speed control
B．a new pattern for painting highways
C．a new way of training drivers
D．a new type of optical illusion
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