Two firms compete in quantities. The aggregate inverse demand is given by P = 300 - 10(Q1 + Q2), where Q1 is the quantity of output produced by Firm 1, and Q2 the quantity of output produced by Firm 2. Firm 1 has a constant marginal cost of 20 per unit of output, Firm 2 a constant marginal cost of 40. Neither firm has fixed costs. Suppose Firm 1 chooses its quantity first, and then Firm 2 chooses its quantity, after having observed Firm 1's choice of quantity. Select all of the following statements that are true. Firm 1 choosing Q1 = 10 and Firm 2 choosing Q2(Q1) = 8 for all Q1 is a Nash equilibrium. Firm 1 choosing Q1 = 15 and Firm 2 choosing Q2(Q1) =5.5 for all Q1 is a Nash equilibrium. O Firm 1 choosing Q1 = 15 and Firm 2 choosing Q2(Q1) =5.5 for all Q1 is a subgame perfect equilibrium. Firm 1 choosing Q1 = 10 and Firm 2 choosing Q2(Q1) = 8 for all Q1 is a subgame perfect equilibrium