OG-37. If the airspace around centrally located airports were restricted to commercial airliners and only those private
planes equipped with radar, most of the private-plane traffic would be forced to sue outlying airfields. Such a
reduction in the amount of private-plane traffic would reduce the risk of midair collision around the centrally
located airports.

Which of the following, if true, would most strengthen the conclusion drawn in the second sentence?
A. Commercial airliners are already required by law to be equipped with extremely sophisticated radar
systems.
B. Centrally located airports are experiencing overcrowded airspace primarily because f sharp increases in commercial-airline traffic.
C. Many pilots of private planes would rather buy radar equipment than be excluded from centrally located airports.
D. The number of midair collisions that occur near centrally located airports has decreased in recent years.
E. Private planes not equipped with radar systems cause a disproportionately large number of midair collisions around centrally located airports.

怎么也想不明白为什么选E, 求大家指点！

It is the private plains without radar systems that cause a great number of midair collisions around the central airports, therefore, the risk of midair collision would decline if such no-radar private plains were prohibited from using the central airports.

看OG后面的解释。题目第一句话是前提，第二句话是结论。

私人机转走－－》机场collision减少。

A 无关
B 削弱
C 有削弱的意思
D 无关
E 加强 （私人机不带雷达是造成collision 的原因，直接建立因果联系支持）