Observing the opponent's previous pattern – they have thrown paper in rounds 1 and 5, rock appears in rounds 2,4,7, and scissors from rounds 3,6,8 – there seems to be a cyclic pattern where paper appears every 4 rounds. Given that rounds 1 and 5 were paper, it's plausible that round 9 might also be paper. To counter an anticipated paper, I will choose scissors.