(A) ** Allied Powers
(B) Central Powers
EXPLANATIONS BELOW
Concept note-1: -Under President Woodrow Wilson, the United States remained neutral until 1917 and then entered the war on the side of the Allied powers (the United Kingdom, France, and Russia).
Concept note-2: -… World War II the chief Allied powers were Great Britain, France (except during the German occupation, 1940–44), the Soviet Union (after its entry in June 1941), the United States (after its entry on December 8, 1941), and China.
Concept note-3: -These events finally brought the U.S. into the war on the side of the Allies on April 6, 1917. In the months that followed, over four million Americans of all backgrounds entered military service and prepared to go overseas.
Concept note-4: -Wilson cited Germany’s violation of its pledge to suspend unrestricted submarine warfare in the North Atlantic and the Mediterranean, as well as its attempts to entice Mexico into an alliance against the United States, as his reasons for declaring war.