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Of course the simple way around

"Pick the most unsafe environment", followed by pictures of a house, a park, a volcano, a bed.

if you're a spammer is to choose randomly and make four times as many attempts. Which is why catchpas make you type six or more letters giving millions of combinations so you can't do it randomly. To get up to a similar resistance to random attempts with 'pick the unsafe environment' type questions you'd need of the order or eight of them (giving 4^8 or approx 65k combinations). Would you as a user want to fill in 8 of those things?



The key is that you are only presented with one captcha per request. But if you fail too many, you get labelled a spammer.




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