(A) The region along the India-Nepal border where nobody in World War I fought.
(B) *The region along the German-Russian border where Russians and Serbs battled Germans, Austrians, and Turks.
(C) The region of northern Spain where the forces of the Allies and the Central Powers battled each other.
(D) ** *The region of northern France where the forces of the Allies and the Central Powers battled each other.
EXPLANATIONS BELOW
Concept note-1: -The Western Front, a 400-plus mile stretch of land weaving through France and Belgium from the Swiss border to the North Sea, was the decisive front during the First World War.
Concept note-2: -The Western Front was the major scene of fighting between Germany and the Allied Powers of France and Britain. Other Allied forces that participated on the Western Front included Australia, Belgium, Canada, United States, and New Zealand.
Concept note-3: -The Western Front of the European Theater of World War II encompassed Denmark, Norway, Luxembourg, Belgium, the Netherlands, France, and West Germany. The Western Front was marked by three phases of large-scale combat operations.