Answer custom question before being allowed to register

Question

Can I limit new registration to users who are able to answer a custom question that only my users know (anti-spam protection)? The question will always be the same for all users. Thanks

Answer 1

You can make a CAPTCHA plugin, see plugin docs here and captcha section here.

I'm sure somebody made a CAPTCHA plugin that allowed you to write pre-determined questions, which would suit your case very well. But I cannot find it now.