Figure 9-2 The Following Diagram Shows the Domestic Demand and Domestic Supply

Figure 9-2
The following diagram shows the domestic demand and domestic supply in a market.In addition,assume that the world price in this market is $40 per unit.
-Refer to Figure 9-2.Suppose the government imposes a tariff of $20 per unit.Relative to the free-trade outcome,the imposition of the tariff

A) decreases imports of the good by 300 units and increases domestic production of the good by 300 units.
B) decreases imports of the good by 300 units and increases domestic production of the good by 600 units.
C) decreases imports of the good by 600 units and increases domestic production of the good by 300 units.
D) decreases imports of the good by 600 units and increases domestic production of the good by 600 units.