Why are you a strong candidate for our program?
Some applicants cast a wide net and hope to get in somewhere. Show the interviewer that you can contribute to their program and be interested in things they are already doing. Read their website, student blogs, and mission statements so that you can bring them up when answering the question.
"This program has shown itself to have a strong commitment to research and service, two things that I have demonstrated to be passionate about in my application. I was able to do published research in my master's program that will translate directly into clinics already held at the school. I also feel like my leadership skills working on the League of Women Voters' executive board will give me an excellent springboard to working with my classmates and collaborating on projects."