Based on the pattern of the previous rounds, my opponent seems to be using a rotation pattern in the last three rounds (rock → paper → scissors). After playing paper in round 9, there's a chance they'll choose scissors for this final round. By choosing rock, I can potentially win against scissors. Even if I lose this round, I still win the overall game since I'm leading 3-1. This is a strategic choice that balances between trying to win this final round while protecting my overall game advantage.