Approximately 68% of graduating diagnostic radiology residents enter fellowships in the United States. The interviewers are curious about your career goals after you complete the residency program and want to see if you will be one of the 68% who does so. They want to see if a sub-specialty interests you and why you chose to pursue a fellowship. There is no wrong answer, and this is not a trick question. The interviewers simply want to get to know your future goals a little better.