[moshezadka]

It can't work the way you explained it: I just solved your CAPTCHA with 33% success rate (waaay too high for a useful CAPTCHA). Perhaps if you ask for "the three pictures of X animal out of those 9", and you had a database with which animal has which property (and you also ran some fuzz over the images so no two images would ever be the same). I'm still skeptical...

[elliottcarlson]

That would assume that it is multiple choice - however if it's still free form text input, requiring the input to equal "frog" would solve that issue. Text + images + logic would offer a lot more hurdles than just any single one of those.