一道GMAT真实逻辑题，大家一起来做做，讨论下~

Renesmeee

这道题用排除法可以得出答案，但答案我实在无法理解为什么它合理，各位元芳，你们怎么看？

Outbreaks of Rift Valley fever occur irregularly in East Africa, several years apart. When
outbreaks do occur, they kill thousands of cattle. A livestock vaccine against the disease exists but
is rarely used. It is too expensive for farmers to use routinely, and since it is not effective until a
month after vaccination, administering it after an outbreak begins helps very little. Nevertheless,
experts predict that use of the vaccine will increase significantly within the next few years.

Which of the following, if true, provides the strongest justification for the experts' prediction?

A. Rift Valley fever is spread by mosquitoes, but each outbreak is so widespread that it is
impractical to control it by using insecticides.
B. When an outbreak of Rift Valley fever occurs, unaffected countries often refuse to import
livestock from the countries affected by the outbreak.
C. It would take less than a month for producers of the vaccine to adjust their production
operations to cope with a large increase in demand.
D. Many cattle farmers in East Africa are nomadic or live in remote villages, and such farmers, who
have little access to modern veterinary medicine, are particularly hard hit by outbreaks of Rift
Valley fever.
E. Recently published research has shown that certain identifiable climatic conditions are almost
invariably followed, within two to five months, by an outbreak of Rift Valley fever.
答案E

May6670

E选项：最近的研究表明，在将来的2到5个月内，会有气候上的变化，这将会带来RV这个地方fever的爆发。那farmer们知道了这个消息，就会马上去给他们的动物打疫苗啊，反正还来得及，对不？

zhaokai09

这题是因果推理

因：It is too expensive for farmers to use routinely, and since it is not effective until a month after vaccination, administering it after an outbreak begins helps very little.
果（根据因推理出来）：use of the vaccine will remain stable within the next few years.

but the prediction is surprising, there must be some other factors contribute to the result.

so the e is the best choice.