(A) ** Stalemate
(B) Quick victory
(C) Armistice
(D) Great Migration
EXPLANATIONS BELOW
Concept note-1: -In 1917, Germany adopted a defensive strategy on the Western Front to counter the growing strength of the Allies. Despite launching several offensives, and suffering heavy casualties, the Allies achieved mixed results.
Concept note-2: -The First World War is, in part, the story of the battle of the whale against the elephant: each supreme in its own element, but neither able to defeat the other. Thinking in the very broadest terms, it is perhaps not surprising that much of the First World War was spent in stalemate.
Concept note-3: -World War I was a war of trenches. After the early war of movement in the late summer of 1914, artillery and machine guns forced the armies on the Western Front to dig trenches to protect themselves. Fighting ground to a stalemate.
Concept note-4: -The conventional explanation for why the Western Front in World War I settled into a stalemate is that the power of defensive weapons was stronger than the offensive methods employed.