请教lsat 一道逻辑题，请帮忙分析下，谢谢！

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。我有疑惑的是b，为什么是c而不是b?如果说机械问题急剧增加的话，那么人的失误不就不用为这次致命的飞机碰撞负责了吗？

这道题的逻辑理解应是怎样的？请帮忙分析解答，谢谢！

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.

原文说，调查人员认为人为因素不是坠机主要原因。而新出台的调律有可能解释50%的出错。

A说飞机仍然相对安全，不沾

B机械故障已经增加，不沾

C明显抬杠选项，干掉

D飞机不如以前愿意报告机械故障，好歹都是题干有的概念

E机械故障容易被检查出来了，没提过

只留下D