Sentence Correction (SC) | Re: Advanced SC: The increased popularity and availability of televisions

if it says the only one of..., then it's singular.
if it says only one of... (without the), then it's plural.
in the phrase "wolf population", wolf is actually an adjective, not a noun. you can't use a pronoun to stand for an
adjective.
you can't say "such a wolf" or "this wolf" either; those constructions imply that you actually have some particular wolf
in mind.