A cost-effective solution to the problem of airport congesti

[BTGmoderatorDC]

A cost-effective solution to the problem of airport congestion and the pollution it causes is to provide high-speed train service between major cities in China, lying 300 to 800 kilometers apart. This plan would cost far less than the expansion of existing airports and would reduce the number of airplanes clogging airports and polluting the air.

Which of the following, if true, could opponents of the plan most appropriately cite as a piece of evidence for their objection to the plan?


A. In order to maintain current levels of airport congestion, significant repairs of airports must be undertaken.

B. The high-speed trains that would be used as part of such plan cause more pollution per passenger than do planes.

C. The majority of passengers departing from rural airports are flying to destinations in cities over 800 kilometers away.

D. Many new airports are being built in areas that are not yet served by high-speed train service.

E. A large proportion of air passengers in China take short-distance flights.

OA B

Source: Veritas Prep

[Ian Stewart]

The argument says, in part, "let's reduce pollution by replacing planes with trains". That's not a good proposal if trains pollute more than planes, so B is clearly one good answer here.

But this question shares a problematic feature with many prep company questions: it's not clear which of the proposal's goals is most important, nor on what basis its opponents are objecting to it. The argument justifies its proposal because it would "cost far less" than airport expansion, because it would relieve "airport congestion", and because it would reduce air pollution. But if answer D is true, and many new airports are being built in areas currently without trains (which is most areas, since as the stem tells us, trains connecting major cities don't exist right now), that suggests an alternative: do nothing, The new airports alone might relieve the airport congestion, and it clearly costs less to only build those airports, which according to D is happening no matter what else is done, than to both build the airports and either build trains or expand existing airports. So if the goal is to be "cost-effective", D suggests a reason not to go ahead with the train proposal.

I'd still consider B the 'best' answer to the question, but D is too good an answer to be wrong on a real GMAT CR question. In real GMAT CR questions that propose a policy, there is usually one clear goal of the policy, and not three, which makes it easier to tell what kind of answer you're looking for.

[rishab0507]

IMO B

We are looking to weaken the conclusion and we just need to find point which has some correlation with the premise in concept for air pollution,
Choice D and E effectively also weaken the solution but are mostly out of scope to be considered for answer.

B is best asnwer