If you're curious whether they mean you didn't get in this time and you can try again or if they meant that the career is closed or effectively doesn't exist, then you should definitely ask for a clarification.
For the former situation definitely say that you'd keep at it, dedication and persistence are key and essential to the practice and study of medicine. Ask any resident, or med student for that matter!
If it's that the field is closed to you, then offer a career that is similar in someway, something like nursing or a PA, or a job that allows you to interact with people daily, it all depends on you. I know that I'd end up teaching in some way, for many reasons, which you should try to express in the interview if they want: for me teaching has always been important, I've always been in school, even this past year after my BA I've enrolled in courses, and for the daily human interaction present in teaching at all levels. Also, the public is largely and generally ignorant of health issues, in every way they have little idea how to keep themselves healthy and they need a health professional to assist them in applying the new research and the old wisdom/research to their own lives. It is essential that a physician be able to teach their patients, patient education is one of our most important duties!
So that's why I say teaching, but you have to find something you're passionate about and have good reasons, they may not ask why, but if they do, you'd better know!
👍 Best of luck!