单选题 During a single hour, an automatic camera photographed 100 vehicles that were speeding on a one-way road, and police a mile farther down the road photographed 49 vehicles that were speeding. Since every vehicle that passed the automatic camera also passed the police during the hour, the police photographed fewer than half of the vehicles that were speeding when passing them.
Which of the following is an assumption on which the reasoning in the argument above depends?

A、 Fewer than half of the vehicles that were speeding when they passed the police were already speeding when they passed the automatic camera.
B、 Drivers who are not exceeding the speed limit are less likely than drivers who are speeding to reduce their driving speed when they see a marked police car.
C、 Most of the vehicles that were speeding when they passed the automatic camera were still speeding when they passed the police.
D、 More than 100 vehicles passed the automatic camera during the hour in which the automatic camera photographed 100 speeding vehicles.
E、 (E) Not more than 100 vehicles drove past the police during the hour in which the police photographed 49 speeding vehicles.

【正确答案】 C

【答案解析】[解析] 本题推理是由一个事实“自动摄像机拍下100辆超速的汽车，而警察只拍下了49辆”，得出了一个解释性的结论“警察拍下了不到一半的超速的汽车，其推理做了一个假设：没有别的原因导致警察拍下了不到一半的超速的汽车”。若大部分在经过自动摄像机时超速的车辆在经过警察时没有超速，那么就表明警察拍得少主要是由于车不超速了，即上面推理必不成立。所以(C)是一个很好的假设；(A)说明不了任何问题；(B)是一个新的无关比较；(D)、(E)都是无关选项。