Rail Executive: Five years ago we discontinued train service between Lamberton and its suburbs because low ridership caused total fares collected to be substantially lower than the cost of operating the service. it is true that recent population growth in the suburban communities suggests increased potential ridership, nevertheless since most of the newer residents own automobiles, restoring the train service this year would still result in serious deficits.

Which of the following, if true casts the most serious doubt on the rail executive’s argument?

A: once train service along a given route has been discontinued, there are substantial start-up costs associated with restoring service along that route.

B: most of the new residents of Lumberton’s suburbs do not need to travel into Lamberton regularly for shopping or recreation

C: if train service were restored this with increased hours of service there would not be an increase in total ridership

D: A survey conducted last year showed that few people living in Lamberton or its suburbs support increased public funding for mass transportation

E: Recently there have been sharp increases in parking fees in Lamberton and in highway tolls on major commuter routes.
正答是E，我选的D
困惑的是，我应该weaken的是increased potential ridership，还是nevertheless后面的部分？
我感觉应该是前者，因为后面是让步状语从句，前面是主句，是作者的主要观点啊 但是E明显WEAKEN的后者。。。
谁能解释下。。。