GWD-29-Q37 怎么没有找到答案

Rabbits were introduced to Numa
            Island in the
nineteenth century.  Overgrazing by the
enormous population of rabbits now menaces the island’s agriculture.  The government proposes to reduce the
population by using a virus that has caused devastating epidemics in rabbit
populations elsewhere.  There is, however,
a chance that the virus will infect the bilby, an endangered native
marsupial.  The government’s plan,
therefore, may serve the interests of agriculture but will clearly increase the
threat to native wildlife.

Which of the following, if true, most
seriously weakens the argument?

1. There is
        less chance that the virus will infect domestic animals on Numa than that
        it will infect bilbies.
2. There are
        no species of animals on the island that prey on the rabbits.
3. Overgrazing
        by rabbits endangers many of the plants on which bilbies feed.
4. The virus
        that the government proposes to use has been successfully used elsewhere
        to control populations of rabbits.
5. There is
        no alternative means of reducing the rabbit population that would involve
        no threat to the bilby.