The correct answer is: "Established access to overseas markets."
Trade agreements such as GATT (General Agreement on Tariffs and Trade) were critical to U.S. trade policy during the twentieth century because they helped to establish access to overseas markets. These agreements reduced trade barriers such as tariffs and quotas, making it easier for U.S. companies to export their goods to other countries.
By opening up overseas markets, U.S. companies were able to increase their sales and profits, which in turn helped to boost the U.S. economy. These agreements also helped to promote economic growth and development in other countries by providing them with access to U.S. goods and services.
While trade agreements like GATT also addressed other issues related to international trade, such as the regulation of trade in services and intellectual property rights, their main focus was on promoting trade liberalization and reducing trade barriers between countries.