25) What is a pure strategy for the Follower firm? (a) A decision to regulate the market, RE (b) An optimal choice of payment to the Policymaker, r. (c) Whether to enter as a function of the previous payment x. (d) For every combination of regulatory decision (NR or RE) and payment by the Incumbent (x), a decision of whether to enter (FE) or not enter (FN). (e) A choice of whether to regulate or not as a function of the payment x