(A) Great Britain, France, Spain
(B) ** Great Britain, France, United States
(C) France, Germany, United States
EXPLANATIONS BELOW
Concept note-1: -The major Allied powers in World War I were Great Britain (and the British Empire), France, and the Russian Empire, formally linked by the Treaty of London of September 5, 1914.
Concept note-2: -During the conflict, Germany, Austria-Hungary, Bulgaria and the Ottoman Empire (the Central Powers) fought against Great Britain, France, Russia, Italy, Romania, Canada, Japan and the United States (the Allied Powers).
Concept note-3: -The main Allied powers were Great Britain, The United States, China, and the Soviet Union.