Answer and Explanation:
The correct answer is, "D. However, they don't take up a lot of space." The answer is A because if the person was to keep a compare-contrast they would need to talk about both animals. Sentence A talks about both animals, not just a singular animal. It says how both animals don't take up a lot of space. This keeps the compare-contrast theme.
Hope this helped! Have a wonderful day!
**Edit: Note, sorry, sorry, sorry, I just realized after I posted it that I highlighted the wrong part of the text! Sorry!! This should be correct.**