They know you are applying to other schools unless you apply early decision. My interviewer asked where I applied and I told him. He knew from my essay I wanted a rural location and in fact lauged at me when I said I applied to CCOM. He said, "oh yes, Chicago is definitly rural." I told him, rural is my first choice, but I was also applying to places where my husband could find a job more easily. And then we changed the topic. So my opinion, if they ask, tell them in a matter of fact tone and move on.