GMAT Sentence Correction (SC) | Re: Most Biologists- Pronoun Number Agreement

Most biologists agree that, although they are being eradicated for centuries and remain an endangered and much maligned species, the wolf has made a comeback in some Western states.

a.they are being eradicated for centuries and remain an endangered and much maligned species
b.they have been eradicated for centuries, remaining an endangered and much maligned species
c.it had been eradicated for centuries and it remains an endangered species that had been much maligned
d.it was eradicated for