Thank you for your comment, davemccoy!

I truly appreciate it. Yes, the captcha ideas are not perfect. If they compare the route of exploiting the system with the registered bot, or trustless scholarship route, I hoped that they would choose the registered bot or scholarship route. So the latter has to be easy and rewarding enough.

I didn't think about #spt tag. thanks!
Absolutely, I hope that Yabapmatt has a great solution too!