[讨论]OG193,一道削弱题请指教!

193.
Editorial:
The mayor plans to deactivate the city’s fire alarm boxes, because most calls received from them are false
alarms. The mayor claims that the alarm boxes are no longer necessary, since most people now have access to
either public or private telephone. But the city’s commercial district, where there is the greatest risk of fire, has
few residents and few public telephones, so some alarm boxes are still necessary.
Which of the following, if true, most seriously weakens the editorial’s argument?
(A) Maintaining the fire alarm boxes costs the city more than five million dollars annually..
(B) Commercial buildings have automatic fire alarm systems that are linked directly to the fire department.
(C) The fire department gets less information from an alarm box than it does from a telephone call.
(D) The city’s fire department is located much closer to the residential areas than to the commercial district.
(E) On average, almost 25 percent of the public telephones in the city are out of order.

The key is B

这道题的B答案的削弱作用我理解

可是我不明白为什么不能对绿色阴影部分进行削弱,如果对其削弱,E选项不对么?

请指教,谢谢!

the editorial’s argument：commercial district, where there is the greatest risk of fire, has
few residents and few public telephones, so some alarm boxes are still necessary

这是需要weaken的，如果加上E岂不起到了加强作用？

思路：

因：商业区发生火灾的风险最大，居民和公用电话较少

果：商业区需要报警信号箱

分析：有因，果是推测，要weaken所以无果，因+否果：虽然风险最大居民和公用电话较少，商业区仍然不需要报警信号箱=〉他因存在