There are numerous preventive medicine fellowships offered in the U.S., including addiction medicine, medical toxicology, occupational medicine, nutrition and metabolism, clinical informatics, and healthcare executive, to name a few. The interviewers are curious about your career goals after you complete the residency program. 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 just want to get to know your future goals a little better.