13. The method of claim 8 further including a step: annotating said candidate challenge sentence with first content elements for said visual and/or text cues found in said at least one first utterance and with second content elements for said visual and/or text cues found in said least one second utterance.
8. The method of claim 1 further including a step: generating a challenge scenario comprised of said candidate challenge sentence and one or more visual and/or text cues, which challenge scenario is stored in said database.