Your admissions interviewers want to know that you haven't put all your eggs in one basket by only applying to their school. At the same time, they want to accept students who value what Midwestern University has to offer over the other schools they've applied to.
Stress that it'll take more than one rejection to keep you down. Convey your determination and the extent of your planning, and explain that you've developed a strategy in the event of not being accepted into Midwestern University this round or at all. Whether you'd reapply if rejected, get a head start on your studies while taking a gap year, or apply aggressively to other universities in other cities or even internationally, talk about your plan, exhibiting your confidence and drive.