Game tree for a 2 player sequential game. If P1 and P2 both pick up, P1 gets $25 and P2 gets $15. If P1 picks up and P2 picks down, P1 gets $10 and P2 gets $10. If P1 picks down and P2 picks up, P1 gets $15 and P2 gets $5. If both pick down, P1 gets $15 and P2 gets $25. In the game above, what is/are the EFFICIENT sub-game perfect Nash equilibrium? (up,up) (up,down) (down, up) (down, down) No EFFICIENT equilibrium exists