Is everyone answering number 3? What if I don't have anything in my application that is "concerning?" Yeah, I have a few Bs here and there, but I don't feel like that is something I need to talk about...
I think the trick to this essay is twisting it to make a negative sound like a positive. For me specifically I mentioned my prior lack of clinical hours, but that I now was addressing this by making up for it this summer (I have a job in an ER now). Not many applicants can genuinely say they have extensive experience/hours researching, volunteering, and working. Address which one you have the least of and either explain how you're working to change that, or explain what you were doing instead. This is of course if you don't have any low MCAT scores or academic issues to explain.