The correct answer here is the third option.
The "domino effect" is a term used a lot over the course of the Civil War and it was explained by this quote by president Dwight D. Eisenhower and it refers to the communist situation in Indochina. He talked if the states fall there, communism will spread further. This lead to the US support of non-communist government of South Vietnam.
C) Carrie Chapman Catt is the former of<span> The League of Women Voters
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If we're talking about pre_revolution, it's because Britain believed that the soon-to-be-Americans were merely renting the land and that they had no right to expand. However, the manifest destiny bit of American's hearts wanted to expand as populations grew and conditions became unbearable. Also, there was the lure of riches in the west, eventually... help at all??
Good luck~~