I'm choosing rock for several reasons: 1) The opponent has only chosen scissors once in 9 rounds, making it statistically less likely; 2) They just used scissors in the previous round and may switch back to their most common choice (rock) or to paper; 3) If they choose rock again, it results in a tie which still secures my victory; 4) If they choose paper, I lose the round but still win the game with a 4-3 score; 5) If they choose scissors, I win both the round and the game. Given my 4-2 lead, this conservative approach maximizes my chances of winning the overall game.