In Artland,the Opportunity Cost of Producing 1 Tonne of Wheat

In Artland,the opportunity cost of producing 1 tonne of wheat is 2 tonnes of corn,while in Scienceland,the opportunity cost of producing 2 tonnes of wheat is 3 tonnes of corn.What action would leave both countries better off?

A) Artland sells 4 tonnes of wheat to Scienceland in return for 7 tonnes of corn.
B) Artland sells 4 tonnes of wheat to Scienceland in return for 10 tonnes of corn.
C) Scienceland sells 4 tonnes of wheat to Artland in return for 4 tonnes of corn.
D) Scienceland sells 4 tonnes of wheat to Artland in return for 7 tonnes of corn.