Critical Reasoning

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

OA: C
I am yet not convinced why?

richachampion wrote: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?
A. There is less chance that the virus will infect domestic animals on Numa than that it will infect bilbies.
B. There are no species of animals on the island that prey on the rabbits.
C. Overgrazing by rabbits endangers many of the plants on which bilbies feed.
D. The virus that the government proposes to use has been successfully used elsewhere to control populations of rabbits.
E. There is no alternative means of reducing the rabbit population that would involve no threat to the bilby.

Plan: To reduce the enormous rabbit population menacing the island's agriculture, the government proposes to introduce a virus, even though this virus may infect the bilby.
Conclusion: The government's plan will clearly increase the threat to native wildlife.

To weaken the argument, the correct answer must show that the virus will NOT clearly increase the threat to native wildlife.

C: Overgrazing by rabbits endangers many of the plants on which bilbies feed.
Since overgrazing by the enormous rabbit population endangers the bilby's food supply, using the virus to reduce the number of rabbits will HELP the bilby -- WEAKENING the conclusion that the government's plan poses a clear threat to native wildlife.

The correct answer is C.