I'm choosing rock because after our scissors tie in round 2, the opponent may expect me to stay with scissors (as players sometimes stick with the same move after a tie). If they try to counter scissors, they'll play rock, resulting in a tie. However, there's also a chance they'll play paper expecting me to switch to rock, but this is a calculated risk I'm willing to take. Additionally, if they simply repeat their last move (scissors), my rock will win.