I agree with Fig's reasoning, and I got D as well. 0 = -, so that should be fine. X > 0 would never work, as you can see by testing numbers. And X<0 makes sense from the absolute value breakdown I found on the GMAT Club's GMAT Math: Absolute Values. I'd link, but I'm too young by GMAT Club post count. I really like the absolute value info posted on GMAT Club, it's an easy to digest refresher on absolute values.
I blog about the GMAT/MBA experience as it happens to me. Also, Zoolander.