4. (20 points) Consider the following game, where (1 represents the degree to which the players are altruistic toward one another, and where it is assumed that a 2 0: Player 2 D C Player 1 D (1+ (1, 1+ (1) (3, 3a) C (3a, 3) (2 + 211, 2 + 2a) (a) Write down the game for a = 1. Is this game a Prisoners' Dilemma game? (b) For what range of values of a is the resulting game a Prisoners' Dilemma