 The second normal-form game is the normal form representation of the subgame starting from Player 1's second node with actions A and B.For the second normal-form game, the Nash equilibrium of the subgame is (A, X).For the entire game Nash equilibria (DA, Y) and (DB, Y) are not subgame perfect equlibria because the move of Player 2 does not constitute a Nash Equilibrium.