Complex sentence: This advice applies to omnivores such as brown and black bears; the best way to avoid being attacked by the completely carnivorous polar bear is not to enter any area where polar bears live, or at least remain inside a hard-shell vehicle or building.
Split into simpler sentences: This advice applies to omnivores such as brown and black bears. The best way to avoid being attacked by the completely carnivorous polar bear is not to enter any area where polar bears live, or at least remain inside a hard-shell vehicle or building.