Answer: buying of goods among nations
Explanation:
Specialization refers to the method of production in which an economic agent produces limited number of goods in order be more efficient and purchase the goods that it's less efficient in producing from other economic agent.
Specialization encourages trade among countries due to the fact that there's no country that can produce everything, therefore it encourages buying of goods among nations. A nation has to buy the goods that it's less efficient in producing.
