I don't think I can select any of the poll options. I normally have one (at most two) books in progress at one time. I have two nice leather bookmarks which I use for this.

I used to be a dog-earer and spine-bender, but I reformed many years ago (around the time I stopped borrowing library books and started buying my own).
I also used to remember the page number I was up to - I have a pretty good memory for numbers, so this worked quite well for me.