On the Q&A Configuration page in the ACP, the instructions include this:

"Using a large and regularly changed set of questions will yield the best results. "

This is contrary to the advice the Support Team generally gives in this regard.  Having a large number of questions does not increase spam protection.  The question set becomes only as effective as the least effective question.  Moreover, having a number of questions means that when a question is broken, there is no way of knowing which question is bad, and the whole set has to be changed.  The following change to that sentence is suggested:

"Only a single proper question is necessary.  If you start receiving spam registrations, the question should be changed."