问一道大全没有的题

In the nation of Partoria, large trucks currently account for 6 percent of miles driven on
Partoria’s roads but are involved in 12 percent of all highway fatalities. The very largest
trucks—those with three trailers—had less than a third of the accident rate of single-and
double-trailer trucks. Clearly, therefore, one way for Partoria to reduce highway deaths
would be to require shippers to increase their use of triple-trailer trucks.
Which of the following, if true, most seriously weakens the argument?
A. Partorian trucking companies have so far used triple-trailer trucks on lightly
traveled sections of major highways only.
B. No matter what changes Partoria makes in the regulation of trucking, it will have
to keep some smaller roads off-limits to all large trucks.
C. Very few fatal collisions involving trucks in Partoria are collisions between two
trucks.
D. In Partoria, the safety record of the trucking industry as a whole has improved
slightly over the past ten years.
E. In Partoria, the maximum legal payload of a triple-trailer truck is less than three
times the maximum legal payload of the largest of the single-trailer trucks.

答案是A 百思不得其解、

向诸位请教，A到底是怎么回事？