21 questions from 7 subject areas

Hello,

to prepare for a written exam, a Lectora test contains 140 questions from 7 subject areas. The special thing is that Lectora should randomly select 3 questions from each subject area, for a total of 21 questions. For simplicity's sake, let's call the topic areas A, B, C, D, E, F, G. It's not clear to me how I can assign the 140 questions to the topics in Lectora Desktop (perhaps via a group); It is also not clear to me how Lectora can be made to randomly select 3 questions from each of the 7 subject areas. Does anyone perhaps have an idea? Thank you.

greeting

ekmud