Go to ACP>Spambot Countermeasure>Available Plugins. Select Q&A then select Configure. You will be taken to a page that has the space to ADD your Question/Questions
Make the Question relevant to something only you know the correct answer to.
Now for the Answers .. yes that's right, ANSWERS ... I have set MULTIPLE answers yet they are ALL correct to the specific question. By this I mean to do your Question and Answers like below:
QUESTION: What year was Abraham Lincoln born? ANSWERS: 1809-02-12 February 12, 1809 12/02/1809 1809 2 12 Thwelth February Nineteen hundred and nine February twelve nineteen hundred & 9
~Note~ That ALL the answers are correct and that the person or bot trying to register has to get at least ONE correct to get past the Q&A and into your site... So what you say!.. Well then this is where YOU get creative for your own specific question/s.