Oh, that was a version of the question we didn't ship where one or more of the choices was actually wrong, so you would have to leave it out of the final ordering. In that interface you didn't have to select all of the choices.

In this case, the point was to teach users about common mistakes and remind them NOT to do that. If they added this to the sequence they'd get it wrong. We haven't shipped this (yet) for simplicity's sake, but may add it later.

To reiterate, one of the goals of Parsnip is to teach people all the things they shouldn't do, rather than just the right answers. Thanks for reading that memo, by the way.