Final answer:
An economy that engages in international trade and financial exchanges is known as an open economy, which is option (d).
Step-by-step explanation:
An economy that has interactions in trade or finance with other economies is referred to as an open economy. This kind of economy is characterized by its involvement in international flows of goods, services, and financial payments. It contrasts with a closed economy, which does not engage in international trade or financial exchanges with other economies.
A tradebalanced economy is one where the value of exports equals the value of imports, whereas a net foreign investment economy refers to the difference between a country's external financial assets and liabilities. However, in the context of this question, the mention of interactions in trade and finance points to the definition of an open economy, which is option (d).