I'm choosing scissors because the opponent has shown a tendency to play paper after I play rock, which they did in rounds 1, 4, and 7. Since I played rock in round 7, there's a good chance they'll play paper again, which would be beaten by scissors. Additionally, the opponent has played scissors in 3 of 7 rounds, suggesting they favor this move, so playing scissors could at least result in a tie if they continue this pattern.