请教OG-23题

whitecloud

OG p504的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?
B)One-half of all departing flights in the nation's busiest airports head for a destination in a major  city 225 miles away
C)The majority if travelers departing from rural airports are flying to destinations in cites over 600 miles away.

答案是B请详细解释B的正确性和为什么C不对，谢谢了！