Pick one of your weaknesses that is not a necessity for the role. Be candid and humble in your answer recognizing that you really aren't great at something and acknowledging your need to improve. Be sure you have an action plan in place for improving on this weakness too. Perhaps you are watching TED Talks about the weakness, reading the latest-and-greatest book on the subject, or maybe you are taking a seminar at a nearby community center in the near future. We are all human and all have weaknesses, so don't be afraid to share yours!