OG11-3 还是不懂

OG 23题题目如下：
A cost-effiective solution to the problem of airport congestion is to provide high-speed ground transportation between major cities lying 200 to 500 miles apart.The successful implementation of this plan would cost far less than expanding existing airports and would also reduce the number of airplanes clogging both airports and airways.
Which of the following ,if true,could proponents of the plan above most appropriately cits as a piece of evidence for the soundness of their plan?

A. An effective high-speed ground-transportation system would require major repairs to many
highways and mass-transit improvements.

OG的解释说expensive repair ,这里也没有提到expesive？