My b2evolution Version: Not Entered

there is a lot of discussion, docs and plugins about antispam for anonymous comments.

I wonder if instead of all the sophistication described in

http://manual.b2evolution.net/Antispam_tab

I could just have a captcha for comments.

This is basically similar to what is in this forum thread

[url=http://forums.b2evolution.net/viewtopic.php?t=7528]Are You A Human (Turing) Test for commenters[/url]

Is anything as simple as this available as a module?

thank you