For round 2, I want to counter the likely repeated use of 'paper' or adapt to the previous move of the opponent. Given that in round 1 the opponent chose paper (which beat my rock), a good strategy is to choose scissors, as it beats paper. This strategy exploits the possibility that the opponent might stick with paper, and if they try to outguess, I still have a chance to win future rounds. So I choose scissors for round 2.