(B) says, "Deforestation is stopped and the koala becomes extinct."
(B) satisfies the sufficient condition of the politician's claim, but it denies the necessary condition of her claim, so it can't be true according to the politician. However, (B) can still be true according to the biologist's claim. This makes (B) the correct answer choice, as it is consistent with biologist's claim, but not with the politician's claim.
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