4. Consider the following stage game. Suppose it is repeated two times. Assume that past actions are observable, and hence common knowledge. Each player's payoff is the sum of the single-period payoffs. Players do not discount future payoffs. a. Consider the following strategy profile: - Player 1: 11=a and 12={bcifh1=(a,a)otherwise - Player 2: 21=a and 22={bcifh1=(a,a)otherwise Show that this strategy profile is not a SPNE of this repeated game. b. Find a pure strategy SPNE of this game. c. Suppose the stage game is repeated three times rather than two. Find all the non-contingent pure strategy SPNE of this game. d. Again, suppose the stage game is repeated three times rather than two