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。