21. The inverse market demand is given by p(y)=26y. Suppose there are only two firms and both of them have the cost function ci(yi)= 2yi.The firms are playing the infinitely repeated 7 Cournot game.For Grim Trigger Staregy to be a Subgame Perfect Nash Equilibrium of this game, the discount factor must be greater than (Round to the closest number) (a) 0.50 (b) 0.53. (c) 0.57. (d) 0. The answer is B6