Answer:
All of the above
Step-by-step explanation:
International trade happens for a wide variety of reasons. Some of then can be specialisation. When a country specialises in production of the good it has a comparative advantage in, it gains from trade. The gains from trade is one major reason for why countries trade with each other.
Through trade countries can acquire resources which it may not posses or it may get it at a lower relative price from the other country.
Thus, specialisation, purchasing raw materials and buying products that are worth more than what is given up are the major reasons for nations to trade.