Taking hard elective

I’m in my senior year and I’m taking an elective that I currently have a C+ in (DNA science which is a post AP class). I didn’t want to take it and I was put into it because it was the only elective that would fit in my schedule. I can’t drop out out because it will show up as withdrawn failing, so what else can I do about it? Should I discuss it in additional information sections of college applications?

I would not discuss it – it will come off as whining. . Colleges will see that it is a high level class. Try hard to get your grade up to the B range.