My opponent has shown a preference for rock (played in rounds 1 and 3), especially returning to it after losing. Since they just won with rock in the previous round, there's a reasonable chance they'll stick with this winning move. Additionally, choosing paper breaks my sequential pattern of paper→rock→scissors→paper, which would make me less predictable against this high-level opponent. While there's a risk they might anticipate this and play scissors, I believe the higher probability is that they'll play rock again.