that's right, I mean markers will be marking a large amount of different major works...so I'm sure you'll be covering something someone else has covered in some way. It's really hard these days to come up with something entirely original...so just go with what you think you'll be able to convey and present the best. If it's something that interests you, or something that you are passionate about, that passion will probably overide the fact it's been done before...and probably allow you to give a new spin to it. If you do it well, which I'm sure you will, it doesn't really matter what you choose.