Looking at the pattern of play, my opponent has chosen rock in rounds 3, 7, and most recently in round 9. There seems to be a tendency to repeat rock after losing a round (lost round 8, played rock in round 9). However, they might anticipate me choosing paper to counter their recent rock play. Since I've already secured the overall win with 5 victories to 1, I can take a calculated risk. I'll choose scissors, which would lose to rock but beat paper if they try to counter-adjust. This also continues the psychological pattern of switching moves after losing the previous round.