能帮我解答section1-16吗？

呼吸

16. Investigators concluded that human failure was not responsible for the fatal airplane crash last August, and since that time new and more stringent rules for identifying and reporting mechanical problems have been in effect. That accounts for the fact that reports of airplane mechanical problems have increased in frequency by 50 percent since last August.
Which one of the following is an assumption underlying the argument in the passage?
(A) Airplane travel is still relatively safe, despite the increase in reported mechanical problems.
(B) Mechanical problems in airplanes have increased dramatically since last August.
(C) Mechanical problems in airplanes have not increased by 50 percent since last August.
(D) Airlines are less reluctant to report mechanical problems than they previously were.
(E) Mechanical problems in airplanes have become easier to detect since last August.

答案是（C）
我对这一题的逻辑关系，理不清，谁能帮帮忙？^_^

tongxun

呼吸：
这个题目的逻辑线索是这样的：
飞机失事不是人为的错误---机械故障---检查故障更严密---机械故障更少

如果检查出来的机械故障增多后，飞机的情况还没有改善，则说明是人的问题了。

呼吸

谢谢，tongxun。^_^