请教OG-100

请教: OG-100
100. A compelling optical illusion called the illusion of velocity and size makes objects appear to be moving more slowly the larger the objects are. Therefore, a motorist's estimate of the time available for crossing a highway with a small car approaching is bound to be lower  than that it would be with a large truck approaching.

the conclusin above would be more properly drawn if it were made clear that the:
A truck's speed is assumed to be lower that the car's
B truck's speed is assumed to be the same as the car's
C truck's speed is assumed to be higher than the car's
D.mostoris's estimate of time available is assumed to be more accurate with cars approaching than with trucks approaching

E.motorist's estimate of time available is assumed to be more accurate with trucks approaching than with cars approaching

求助：知道答案，但是不知道如何排除D，E？谢谢。

why C is the best ??

写的一大篇又丢了，没力气再打了。

总之本题比较的就是估计的时间，而非现实与估计的差。

详见11OG