The only thing I can think of is that you might respond with "my score doesn't adequately reflect my academic performance." But that welcomes the opportunity for the second question of "well, why didn't you retake?"
I really doubt you would ever actually get this question in an interview.
Why was your score low? Does it represent your best effort after 2-3 months of preparation? If not, then why not?Do you believe your MCAT scores accurately represents your potential to succeed in medical school? Why or why not?
If my score is low, how do I answer this?
1) Figure out why you didn't do well on the MCAT, and formulate a decent reason not based upon blaming God or AAMC (is that redundant?). This includes a reasonable explanation why you didn't re-take if you feel it doesn't reflect your abilities.
2) Read the threads all over this site on HighGPA/LowMCAT (assuming that is what you have) and look at how they explained in it interviews.
3) Incorporate the facts of your situation with how others have dealt with this and try to spin it to the best you can.
4) Realize if you are still writing secondaries you late in the cycle so do 1-3 quickly and efficiently.