why is the answer d

School of Economics, University of Cape Town Suppose that workers in Boatland can produce either 50 units of wheat or 250 units of fish per year, and workers in Farmland can produce either 250 units of wheat or 50 units of fish per year. Political pressure prevented trade between the two countries. As a result, Boatland produces and consumes 25 units of wheat and 125 units of fish per year while Farmland produces and consumes 125 units of wheat and 25 units of fish per year. If trade were to occur, each country would specialise in the product in which it has a comparative advantage. Assuming that the two countries do specialise and trade with one another, the combined output of the two countries would increase by A. 25 units of wheat and 25 units of fish. B. 50 units of wheat and 50 units of fish. C. 75 units of wheat and 75 units of fish. D. 100 units of wheat and 100 units of fish. E. 125 unit of wheat and 125 units of fish