Based on pattern analysis, the opponent has recently played a rock-scissors-paper sequence. If they continue this cycling pattern, they would play rock next, but that's too predictable. More likely, they'll anticipate I might play paper (to beat their potential rock) and therefore play scissors to counter. By choosing rock, I can counter their potential scissors play. Additionally, the opponent has shown a preference for rock overall (played 4 times), suggesting they might return to their comfort choice in this decisive final round.