Concept:Internal trade means the exchange of goods and services within the boundaries of a single country.
Explanation:Buying and selling activities conducted inside a nation are known as internal trade.
These transactions happen between buyers and sellers located in the same country.
Foreign trade refers to trade between one country and another country.
International trade also involves the exchange of goods and services across national borders.
Barter trade is a direct exchange of goods for goods without using money.
Only internal trade matches the idea of trade happening within a country.
Therefore, the correct option is internal trade.
Answer:D. internal trade