Looking at the previous rounds, I've noticed the opponent has chosen rock twice (rounds 1 and 3) and scissors once (round 2). They seem to favor rock, especially after they just won with it in round 3. Since they experienced success with rock last round, there's a good chance they'll stick with it. Therefore, I'll choose paper to counter their likely rock choice. Additionally, I've had success with paper in round 1, which might make my opponent less likely to expect me to use it again so soon.