In the previous rounds, my moves and the opponent's moves have always been identical: rock, paper, scissors, rock. This pattern can be interpreted in two ways: either the opponent is simply mirroring my moves, or he is following a cyclic pattern (rock, paper, scissors, repeating). If it's the cyclic pattern, then his round 5 move would be paper (after rock in round 4), which scissors would beat. On the other hand, if he’s just mirroring, any move will tie. Since scissors gives a chance for a win under the cyclic interpretation and only a tie under mirroring, I choose scissors for round 5.