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?
What would strengthen the experts' prediction? The correct answer will likely tell us a reason to believe:
(1) that the farmers will use the vaccine despite the high cost or
(2) that vaccines somehow still helpQuote:
(A) Rift Valley fever is spread by mosquitoes, but each outbreak is so widespread that it is impractical to control it by using insecticides.
Doesn't strengthen the experts' prediction. Insecticides = out of scope.
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(B) When an outbreak of Rift Valley fever occurs, unaffected countries often refuse to import livestock from the countries affected by the outbreak.
Out of scope. We are not concerned with what unaffected countries do.
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(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.
Doesn't explain why experts believe the vaccine will be used widely in the next few years. C is out.
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(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.
This doesn't explain why experts believe the vaccine will be used widely. We're told the vaccines are expensive and are not effective until a month after their use. This choice doesn't give us a reason to believe the experts' prediction.
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(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.
This matches our second point. If we can predict when an outbreak will occur, we can properly time the use of a vaccine! E is the clear winner.