Suppose that Spain and Austria both produce fish and stained glass. Spain's opportunity cost of producing a pane of stained glass is 4 pounds of fish while Austria's opportunity cost of producing a pane of stained glass is 10 pounds of fish.

By comparing the opportunity cost of producing stained glass in the two countries, you can tell that as a comparative advantage in the production of stained glass and has a comparative advantage in the production of fish.

Suppose that Spain and Austria consider trading stained glass and fish with each other. Spain can gain from specialization and trade as long as it receives more than of fish for each pane of stained glass it exports to Austria. Similarly, Austria can gain from trade as long as it receives more than of stained glass for each pound of fish it exports to Spain.

Based on your answer to the last question, which of the following prices of trade (that is, price of stained glass in terms of fish) would allow both Austria and Spain to gain from trade? Check all that apply.

A. 9 pounds of fish per pane of stained glass
B. 7 pounds of fish per pane of stained glass
C. 16 pounds of fish per pane of stained glass
D. 1 pound of fish per pane of stained glass