This section is truely optional and for most applicants and should be blank, for almost any school. You would answer this question if therer where questionable aspects in your profile and/or essays you wrote that require clarity. For example, gaps in your resume, no longevity in your job(s), being fired, low grades, disconnect between your goals and actions you have taken thus far. I can't provide you with a comprehensive list because gaps are unique to the individual. The best general suggestion I can give you is to try to identify detrimental aspects or holes in your application and then simply ask yourself if you conveyed a logical explanation of why such aspects are there and if you were able to mitigate the impact. If not, use essay 6. Hope this helps.