This plugin fights comment and registration spam on your website. This plugin is based on the Open Source WP No-Bot plugin at http://www.compdigitec.com/apps/wpnobot by Compdigitec.
This plugin is authored by Seravo Oy, which specializes in open source support services and among others is the only company in Finland to provide WordPress Premium Hosting.
Source available at https://github.com/Seravo/wp-spam-question-filter