Mahan suggests that an end to isolation is necessary because

Alfred Thayer Mahan was a United States naval officer and historian. His book  The Influence of Sea Power Upon History, 1660–1783 (1890) was widely acclaimed, especially in Europe.

In his book, Mahan argued that the power a nation has depends predominantly on its dominance of the seas. He also argued that the economic future of the U. S. depended on getting new markets abroad. This required an end to isolationism. It also required a powerful navy to protect these markets from foreign rivals.

because its important to learn about other countries and how high tech they are compared to us. also its good to learn about other cultures and how ours differs and in common also we need to learn about companies that we still buy since they ship it here.

answer; (c) slaves brought to the americans from africa;