I found that curious, as well, and think another commenter's suggestion makes the most sense. EDIT: As opposed to robo-detectors that ask seemingly-nonsensical questions such as, "Are you a human?"

    spindritf 32 minutes ago
    Maybe as a way to mark people who didn't treat it very seriously?

https://news.ycombinator.com/item?id=8367812

Cat is a dumb option. That being said, the list order seems randomized.