Species that are extinct are species that no longer has any specimen alive anymore, which means that this living beings won't ever be present on Earth again. But it doesn't happen out of nowhere. The species goes through some of all of those definitions, as a warning that we must act to avoid extinction. As vulnerable are species that are facing a high-risk, but stil it isn't an imminent risk, so C it's not the closest. Threatened are species that are likely yo become endangered, not extinct, so D isn't the answer as well. Special concern are species that aren't even threatened or endangered yet, so E isn't the answer too. Endangered species are facing an imminent danger of becoming extinct, but still being extirpated may be even more concerning, because extirpation can be a consequence of overlooking a situation of endangered species and it is also a way in which a species can be extinct (they tend to disappear from specific areas until there are no more areas where they can be found anymore). So, the correct answer is a) Extirpated.