Answer:
b.both parties are made better off.
Explanation:
People voluntary to trade when they will better off after the trade. Since individual or nation has different proficiency and endowment resources, the ability to produce some product will be different for each country.
For example, German people are skillful of making beer. They have efficient production. Whereas France have expertise in making perfume. It is reasonable for German people to buy perfume from France since it is cheaper and has better quality than making it themselves. On the other hand, if french want to drink beer, it is cheaper to buy from Germany. Thus, both Germany and France will be better of after the trade.
