So we've all been there before--you try answer choice A, and it doesn't work--i.e, you try using real numbers and you're able to get two different answers to the question. (Cross off A and D).
You try answer choice B, and it doesn't work for the same reason (two different answers). Cross off choice B.
Now, time to decide between C and E.
For some reason, I've seen a lot of students get sloppy at this point. I've heard a lot of students say "well it must be C" or "well it must be E" without actually checking their figures and trying to get two different answers, the same way you would with step one and step two. There are plenty of questions that look like they must be "C" at first glance, but they turn out to be "E," and vice-versa. My point here is that you should never assume. You've come this far--don't give up now! Trust your Data Sufficiency techniques, use real numbers whenever possible and don't try to cut corners.