The Admissions Committee at the University of Missouri wants to know that you have thought out all options and scenarios if you are not accepted to the MU College of Veterinary Medicine. Your approach to answering this question should show the interviewers that your interest in the field of vet medicine reaches deeper than your initial acceptance into veterinarian school.
If you are not accepted, show that you will take a different path, perhaps into veterinarian pharma or military dog care. Or, you can let the interviewers know that one rejection won't stop you. In that case, talk about your plan to reapply if rejected.
Whatever the path you choose, you must show the interviewers that you have the confidence and drive required to reach your goals. It would take more than one rejection to keep you down.