>>17In general, multiple choice captchas are considered terrible, because you always allow automated solvers at least a 1/n chance. Even for a 10 choice problem, that's a 10% false negative rate, which is unacceptable, combined with annoyance on the human end of looking at too many options. The goal is a system where you just ask "How many fingers does a human hand have?" and then accept answers that are equivalent to "5".