Replying to a request from
AR15J:
First, this is not one of ours! Manhattan Review is a different company, so I don't want to take credit for this one.

I see two flaws in this question:
*The use of "even though" at the beginning isn't the best. We're saying that
even though books portray them this way, grizzlies are
still able to be sociable. This implies that grizzlies somehow manage to be sociable despite their portrayal in the media. We'd be better off with a more neutral contrast word, such as "while" or "although."
*Answer A shouldn't have a comma before "roaring." It's clearly meant to modify "bears," not the preceding clause/action, and we generally omit the comma for noun modifiers in -ing form unless we need to add a comma for clarity.
Disregarding those flaws, A is the best choice we have for the following reasons:
*There's nothing wrong with the use of "they" in A. Although it's true that when in doubt we assume that a pronoun refers back to the subject of the clause, there's no doubt here. No reasonable reader is going to be confused about whether books or bears are playful and sociable. This is definitely a non-issue.
*The use of the redundant "peak tops" in C is enough to make it wrong.
*The rearrangement in C is not really helpful. We don't need to make bears the subject, and to accomplish this, we've had to move the modifiers in a way that impedes the flow of ideas. The modifier "as savage animals" has been separated from the verb "portray" by two prepositional phrases. This isn't so much wrong as annoying and unnecessary. There may be sentences where that form is needed, but we don't need it here.