I think, of the three, I'd prefer the first as a more...well-mannered (?) option. The second seems the most likely to work, but even as a CW answer, it *feels* inherently rude to 'copy' somebody's answer.

Unfortunately, so far as I know, the diamond-mods have the ability to [change an 'answer' to a comment](https://meta.stackexchange.com/questions/35175/should-moderators-be-able-to-convert-answers-into-comments), but not the reverse so far as I'm aware.

It's also worth noting that my personal bias is against the mis-leading statistics of an answered (even if only in comments) question being considered unanswered by the site's design/metrics.