Based on the previous rounds, my opponent chose rock then scissors. There's a possibility they might continue rotating through options and choose paper next, but they might also anticipate I'd expect that pattern and stay with scissors. Since we just had a tie with scissors in round 2, my opponent might expect me to switch to paper, so they could stick with scissors to counter that. By choosing rock, I can beat scissors if they repeat their last move, and at worst get a tie if they also choose rock. While this risks losing to paper, I'm currently ahead in score which gives me some room to take a calculated risk.