LSAT,test 9,13

[freshmanduke]

13. Five years ago, during the first North American outbreak of the cattle disease CXC, the death rate from the disease was 5 percent of all reported cases, whereas today the corresponding figure is over 18 percent. It is clear, therefore, that during these past 5 years, CXC has increased in virulence.
Which one of the following, if true, most substantially weakens the argument?
(A) Many recent cattle deaths that have actually been caused by CXC have been mistakenly attributed to another disease that mimics the symptoms of CXC.
(B) During the first North American outbreak of the disease, many of the deaths reported to have been caused by CXC were actually due to other causes.
(C) An inoculation program against CXC was recently begun after controlled studies showed inoculation to be 70 percent effective in preventing serious cases of the illness.
(D) Since the first outbreak, farmers have learned to treat mild cases of CXC and no longer report them to veterinarians or authorities.
(E) Cattle that have contracted and survived CXC rarely contract the disease a second time.

the answer is D, but I choose B
想請問大家的意見
thanks

[liwuu]

剛開始爆發cattle disease CXC其官方死亡率為5％,目前則上升到18％
所以推論其疾病越來越毒
問weaken...
答案D說明這幾年來農夫已經可以自行處理mild CXC且不會向當局提出病例,所以死亡率提高的原因在於獲報的都是嚴重性的CXC(致死率較高),因此死亡率提高不是因為病毒變毒...

答案B說明很多之前通報因為CXC而死亡的案例實際上是因為其他疾病所造成
如此一來應該死亡率會降低而非如題目所述死亡率提高...

[freshmanduke]

I see, thanks for help!