D. U.S. teetering on isolationism and only being involved in world affairs if it directly affects the U.S
Explanation:
The policy of isolating one's country from the affairs of other nations by preventing forming alliances is called the Isolationism. Supporters of this policy are called isolationists. They advocate devoting a nations resources to its advancement by avoiding binding responsibilities to other nations and maintaining peace.
American isolationism began in colonial period as the American colonists wanted to avoid involvement with European powers that had denied them economic and religious freedom and kept them engaged in wars. It only formed alliance with France during the War of Independence, that too was initially opposed by the congress.
President George Washington also advocated for the isolationism and mentioned it in his farewell address. Thomas Jefferson also talked about it in his inaugural address and US practised isolationism in the19th century. It finally ended in 20th century.
