4. Two players are engaged in the infinitely repeated "Prisoner's dilemma" game whose stage is shown below. a Find the set of all feasible individually rational payoffs. b) Construct a trigger strategy SPE that would allow the player obtain the payoff of (2,2) in the game. c) Find the smallest value of the one-period discount factor & for which the SPE from b) is possible. C D C 2,2 0,3 D 3,0 1,1