Interviewers usually pose this question because they may be interested in knowing how serious you are in pursuing a given academic or professional field. Although there is no "right answer" to this question, evaluate your plans for the future and be sure to give an answer that is insightful in that it shows that you have a plan to build upon your professional skills even after your internship. Another solid strategy is to play up the role of the internship opportunity to influence your career goals. Your career goal may simply be to learn as much about ‘x’ as possible in this internship to know if it is something you’d like to pursue a career in.