28-17: 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

My best guess is B? Do you have any input?