One way for reducing commuting time for those who work in the cities

Official Explanation

The question is one that tests the validity or strength of a causal inference. Often such arguments can be attacked by finding intervening causal linkages, that is, variables that might interfere with the predicted result. (A) cites such a variable. If the traffic problem is created by commercial traffic that will not be reduced by toll increases, then the proposed increases will not solve the problem.

(C), too, is such a variable. It suggests that the proposal is essentially self defeating.

(D) undermines the claim by arguing that the deterrent effect of a price increase is simply not significant, so the proposal will have little, if any, effect.

(E) attacks the argument on a different ground. The ultimate objective of the plan is to reduce commuting time. Even assuming a drop in auto traffic because some commuters use public transportation, no advantage is gained if the public transportation system cannot handle the increase in traffic.

(B), however, does very little to the argument. In fact, it could be argued that (B) is one of the predicted results of the plan: a drop in the number of autos because commuters begin to car-pool.

The correct answer is (B).