Answer: D: Zoos utilize habitats to educate the visiting public.
Explanation: As much as I hate that sentence, it's absolutely the most formal of each of these options. Generally, using the first person is a sign that an author is using an informal literary style (which eliminates answers A and B.) Also, saying things like "cool," "awesome," or "rad" are clear signs that a writing style is informal. TL;DR: Do the one that sounds the most annoyingly boring. You'll almost always be right.