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.
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
Answer 是E, 請問如何排除A跟B呢
A--> 無法透過控制病原的方式減輕疫情, 所以需要疫苗 (似乎合理?)
B--> farmer的生意被impact, 所以increase demand for vaccine (似乎也合理?)
Thanks
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