18. Table: Cell Service Mr. Brooks Cell Service A Cell Service B Ms. Gertrude 50, 50 (10, 5) (75, 75) Refer to the table. Mr. Brooks and Ms. Gertrude are good friends who like to talk on the phone. Each is deciding on a cell phone service to sign on with, where each service offers free unlimited calls to other customers who subscribe to the same service. The payoff table shows the rewards to Mr. Brooks and Ms. Gertrude from choosing either cell service A or B. a. What is(are) the Nash equilibrium(s) in this coordination game? (1 pt.)