费费逻辑宝典61的困惑

stoneren

我的答案是C，无法理解原答案D。
首先，请给个中文解释；其次，解释答案。谢谢！
61. 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.

stoneren

sorry,我的答案是D，无法理解的是原答案C

franklin

报告的机械问题上升50%是因为实行了新的严格的规则使原来不报告的问题报告上来了。言外之意就是机械问题并没有上升那么多。如果是机械问题上升了50%，那就不是新规则的作用了。
排除它因型。