LSAT-4-1-9

dreadpower

9. It is not known whether bovine spongiform encephalopathy (BSE), a disease of cattle invariably deadly to them, can be transmitted directly from one infected animal to another at all stages of the infection. If it can be, there is now a reservoir of infected cattle incubating the disease. There are no diagnostic tests to identify infected animals before the animals show overt symptoms. Therefore, if such direct transmission occurs, the disease cannot be eradicated by______
Which one of the following best completes the argument?
(A) removing from the herd and destroying any diseased animal as soon as it shows the typical symptoms of advanced BSE
(B) developing a drug that kills the agent that cause BSE, and then treating with that drug all cattle that might have the disease
(C) destroying all cattle in areas where BSE occurs and raising cattle only in areas to which BSE is known not to have spread
(D) developing a vaccine that confers lifelong immunity against BSE and giving it to all cattle, destroying in due course all those animals for which the vaccine protection came too late
(E) developing a diagnostic test that does identify any infected animal and destroying all animals found to be infected
    答案是A，我觉得按照A的做法不好。
     文章说了，无法检测出来牛是否已经被感染该病毒，也不知道该病毒是否能传染（在病毒的各个阶段）。按照A的做法，表现出来就杀掉，那么如果这个病毒能感染，牛群就会被杀光。

     我觉得是E，研究疫苗，杀掉已经感染的。

joice

you want to follow the direction in which the passage is going.
E is not in line with the evidence  that  there are no diagnostic tests to identify infected animals before the animals show overt symptoms.

cranberry

cos no test can identify weather the cattle is infected before it shows symptom of bse, and if direct infection exists ,so if we only kill the cattles showing symptoms of bse, we may leave some cattles infected but showing no symptoms,so these cattles may infect others.