Final answer:
Among the listed reasons, a strong U.S. dollar making exports less affordable in foreign markets is not an exception; it's a valid reason for the low level of U.S. exports since it would increase prices abroad and reduce competitiveness.
Step-by-step explanation:
The question addresses reasons for the low level of U.S. exports relative to other countries. The reasons cited for a low level of exports include limited ambition by American business owners, lack of knowledge of market opportunities abroad, perceived lack of necessary resources, and that marketing domestically is easier than exporting. However, a strong U.S. dollar would actually lead to more expensive exports, which is a valid reason for low levels of exports. This is because a strong dollar can increase the price of U.S. goods in foreign markets, making them less competitive compared to locally produced goods or those from countries with weaker currencies.
The United States' large economy also means there is less need to trade internationally compared to smaller economies that are part of the European Union, which benefits from barrier-free trade among member states.