What theme refers to exporting and importing goods across a country or ocean? Human/environment interaction place region movement location

the theme that refers to exporting and importing goods across a country or ocean is movement.

Exporting is international trade of a good or service produced in one country that is sold into another country. The seller of such goods and services is an exporter; the foreign buyer is an importer. Export of goods often requires the involvement of customers authorities. From the buyer's point of view an export is an import.

Importing is the receiving country trade of an export from the sending country. Importation and exportation are the defining financial transactions of international trade. In international trade, the importation and exportation of goods are limited by import quotas and mandates from the customs authority. The importing and exporting jurisdictions may impose a tariff on the goods.

Hope I helped.

because the center-south is called the heart of the country

81 is a composite number.