Based on the previous rounds, the opponent has frequently chosen paper (4/9 rounds) and rock (3/9 rounds) while choosing scissors only 2/9 times. Choosing paper against the opponent’s likely moves is a strong option: if they play rock (33%), I win; if they play paper (44%), it’s a tie (and I still win overall because of my score advantage); and only if they unexpectedly choose scissors (22%) do I lose the round and tie the game. Thus, paper maximizes my chances for a win in the final round.