Meanwhile, the other employee proposes using a different strategy to achieve the government's goal of reducing pollution in the area from 12 units to 6 units. This employee suggests that the government issue two pollution permits to each firm. For each permit a firm has in its possession, it can emit 1 unit of pollution. Firms are free to trade pollution permits with one another (that is, buy and sell them) as long as both firms can agree on a price. For example, if firm X agrees to sell a permit to firm Y at an agreed-upon price, then firm Y would end up with three permits and would need to reduce its pollution by only 1 unit while firm X would end up with only one permit and would have to reduce its pollution by 3 units. Assume the negotiation and exchange of permits are costless. Because firm Y has high pollution-reduction costs, it thinks it might be better off buying a permit from firm Z and a permit from firm X so that it doesn't have to reduce its own pollution emissions. At which of the following prices is firm Z willing to sell one Of its permits to firm Y, but firm X is not?