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.


My American friend and I have been arguing for 2 days...Pls explain your answer!

pretty sure it is E.
Problem with vaccine is 1. expensive, 2. one month effective delay
E negates #2 since we know that it will occur two to five months in advance.

Mouse,

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haha thanks sondenso .. FYI its not a mouse - its a daemon.

Because he said A, but I come to E

He argued that farmers can not use insecticide, therefore they must use vaccine otherwise no ways to protect their cattles. What's wrong with this reasoning???

Besides, E just says that the outbreak will occur in two-five months, yes it just ensures that if the farmers use the vaccine, there will be enough time for vaccine to prove its effectiveness. Nothing can ensures that the farmers will use it.

I dont have strong counter-argument for his reasoning!

Besides, OA is A

But your previous reasoning is so perfect! I dont see any thing's wrong with it.
I dont always believe in OA. It can be wrong.

The farmers cannot use insecticide, but can use different method (non-vaccine) altogether.
How about a method that stop the start of mosq outbreak by eliminating all stilled-water pond all over the places...?

The statement doesn't restrict that there are only two methods!

A has less to do with the argument as a whole than E. I still go for E.

I was first leaning towards E too and I would have done the same if it would appear on Real GMAT.

The conclusion is that the use of the vaccine will increase even though its really not practical to use.

We need to look for something that would tell us that besides all the impractical use of vaccine the demand for the vaccine will improve.

Now A supports the conclusion more strongly than E.

In E: research suggest that its possible to predict the outbreak but nothing states that the research is 100 % correct - it may be right or may be wrong.

A states that any insecticide is ineffective thereby forcing the farmers to use the vaccine and hence the demand will increase.

From 32 Tests Set. I am practicing on it. But my friend said that do not believe 100% on this set's answers. In fact I discover several mistakes in this Set.