The interviewer may be indicating that you have failed to convince them so far that you are one of the best student to select. Alternatively, they may just be asking you to pitch yourself. Either way, what they’re really looking for is for you to give them at least one good reason why they should be admitting you and not someone else. To successfully answer this question you need to have a clear understanding of what the perfect student for the course would be and how best you match that description more so than the other applicants. But don’t go overboard in your answer you probably don’t know anything about the other applicants.